Early cytokine response of gnotobiotic piglets to Salmonella enterica serotype Typhimurium

Abstract

-Cytokine response against Salmonella Typhimurium is traditionally studied in conventional animals. Germ-free animals, however, enable to study response against infection without background effect of other microorganisms. Plasma and ileal inflammatory cytokines in germ-free piglets orally infected with virulent LT2 strain or, with a non-virulent SF1591 rough mutant were quantified by ELISA. In plasma and ileal washes, IFN-γ levels significantly increased in both infected groups. TNF-α and IL-18 were mostly missing in plasma 24 h after infection. In the ileum, IFN-γ, TNF-α, and IL-1β were induced mainly by the virulent strain, whereas IL-18 was induced in highest quantity by non-virulent Salmonella. These data confirmed an important role of IFN-γ, as well as other inflammatory cytokines in early stage of salmonellosis.Salmonella Typhimurium / gnotobiotic piglet / cytokine Résumé -La réponse précoce en cytokines contre Salmonella enterica Typhimurium chez des porcelets gnotobiotiques. La réponse en cytokines contre Salmonella Typhimurium est traditionnellement étudiée chez les animaux conventionnels. Les animaux sans germes, cependant, permettent d'étudier la réponse à l'infection sans avoir le bruit de fond dû à d'autres micro-organismes. Les cytokines inflammatoires du plasma et de l'iléon chez des porcelets sans germes, infectés oralement par la souche LT2 ou avec un mutant non virulent de SF1591, ont été quantifiées par ELISA. Dans le plasma et dans les lavages de l'iléon, les taux d'IFN-γ ont augmenté significativement chez les animaux des deux groupes infectés. Le TNF-α et l'IL-18 étaient présents en faibles quantités dans le plasma 24 heures après infection. Dans l'iléon, l'IFN-γ , le TNF-α et l'IL-1β ont été induits principalement par la souche virulente, alors que l'IL-18 a été induite en plus grande quantité par les salmonelles non virulentes. Ces données confirment le rôle important de l'IFN-γ et des autres cytokines inflammatoires dans les stades précoces de la salmonellose.Salmonella Typhimurium / porcelet gnotobiotique / cytokine 291 Vet. Res. 33 (2002) 291-297

The effect of intestinal colonization of germ-free pigs with Escherichia coli on calprotectin levels in plasma, intestinal and bronchoalveolar lavages

“…In conventional pigs, calprotectin levels are much higher, the effect of colonizing bacteria in these animals would be, however, imperceptible due to the colonization resistance of endogeneous microflora. The presence of calprotectin in germ-free pigs reflects constitutive secretion of this protein even if young germ-free piglets lack inflammatory cytokines in their gut (Splichal et al, 2002a). We have shown recently that a calprotectin response can be induced already in foetuses after intra-amniotic infection (Splichal et al, 2002b).…”

Immune Response of Gnotobiotic Piglets against Mycoplasma hyopneumoniae

“…The use of Mhp-gnotobiotic piglets are unique model to investigate the precise immune responses against a target microbe, because the background levels of cytokines induced by endogeneous micro-organisms are negligible but animals respond well to inflammatory signals [23,28]. Gnotobiotic infection models have previously been used for Mhp [16,11] and successfully used to develop pneumonia in this study, too.…”

“…The absence of other microorganisms excludes competition and complex interactions among microbes known as colonization resistance [29]. It excludes also background levels of cytokines that are induced by a plethora of endogeneous micro-organisms and simplifies the interplay of mediators [23]. GF pigs are immunologically immature [15], lack maternal immunoglobulins and produce only traces of own antibodies [27].…”

Rapid Protection of Gnotobiotic Pigs against Experimental Salmonellosis following Induction of Polymorphonuclear Leukocytes by AvirulentSalmonella enterica

“…Factors which may cause the different pathologies observed in the intestines of diseased and protected pigs may be due to differential ileal cytokine expression. Gnotobiotic piglets inoculated orally with virulent S. enterica serovar Typhimurium LT2 have elevated levels of ileal gamma interferon, tumor necrosis factor alpha, and IL-1␤ compared to those in gnotobiotic piglets inoculated with an avirulent rough mutant of S. enterica serovar Typhimurium SF1591 (44). These Th1 cytokines have been shown to cause severe intestinal inflammation and pathology in murine intestinal epithelia (34).…”