Location: Toxicology & Mycotoxin ResearchTitle: Effects of Salmonella enterica ser. Enteritidis and Heidelberg on host CD4+CD25+ regulatory T cell suppressive immune responses in chickens
|ACEVEDO-VILLANUEVA, KEILA YANIS - University Of Georgia|
|AKERELE, GABRIEL - University Of Georgia|
|MORTADA, MUHAMMAD - University Of Georgia|
|SELVARAJ, RAMESH - University Of Georgia|
|APPLEGATE, TODD - University Of Georgia|
|Kogut, Michael - Mike|
Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2021
Publication Date: 11/29/2021
Citation: Shanmugasundaram, R., Acevedo-Villanueva, K., Akerele, G., Mortada, M., Selvaraj, R.K., Applegate, T.J., Kogut, M.H. 2021. Effects of Salmonella enterica ser. Enteritidis and Heidelberg on host CD4+CD25+ regulatory T cell suppressive immune responses in chickens. PLoS ONE. 16(11). Article e0260280. https://doi.org/10.1371/journal.pone.0260280.
Interpretive Summary: The upregulation of T regulatory cells by Salmonella was antigen-specific and the immune response was observed only in the gut where Salmonella had colonized until 32 dpi. Salmonella infection of chickens though induced T cell IL-2 and IL-1ß transcription at 3 dpi, there were no differences in the studied cytokine transcription of T cells between the control group and Salmonella infected groups after 11 dpi. S. Enteritidis and S. Heidelberg infection at 3 d of age induces a persistent infection through inducing T regulatory and altering the IL-10 mRNA transcription of T regulatory cells in chickens between 3 to 32 dpi and chickens become asymptomatic carriers of Salmonella after 18 dpi.
Technical Abstract: Poultry birds infected with Salmonella, though mount an immune response initially, the immune responses eventually disappear leading to poultry acting as a carrier of Salmonella. The hypothesis of this study is that Salmonella infection induces T regulatory cell and suppress host T cells locally in the gut to escape the host immune responses. An experiment was conducted to comparatively analyze the effect of S. enterica ser. Enteritidis (S. Enteritidis) and S. enterica ser. Heidelberg (S. Heidelberg) infection on CD4+CD25+ T regulatory cell properties in chickens. A total of 144 broiler chicks were randomly distributed into three experimental groups of non-infected control, S. Enteritidis infected and S. Heidelberg infected groups. Chickens were orally inoculated with PBS (control) or 5x106 CFU/mL of either S. Enteritidis or S. Heidelberg at 3 d of age. Each group was replicated in six pens with eight chickens per pen. Chickens infected with S. Enteritidis had approximately 6.2, 5.4, and 3.8 log10 CFU/g, and chickens infected with S. Heidelberg had 7.1, 4.8, and 4.1 log10 CFU/g Salmonella in the cecal contents at 4, 11, and 32 dpi, respectively. Both S. Enteritidis and S. Heidelberg were recovered from the liver and spleen 4 dpi. A 4, 11, and 32 dpi, chickens infected with S. Enteritidis and S. Heidelberg had increased CD4+CD25+ cell numbers as well as IL-10 mRNA transcription of CD4+CD25+ cells compared to that in the control group. CD4+CD25+ cells from S. Enteritidis- and S. Heidelberg-infected chickens and restimulated with 1 µg antigens in vitro, had higher (P < 0.05) IL-10 mRNA transcription than the CD4+CD25+ cells from the non-infected controls and restimulated with 1 µg antigens in vitro at all the time points studies suggesting that the increased T regulatory cell activity post-Salmonella infection was antigen-specific. Though at 4dpi, chickens infected with S. Enteritidis and S. Heidelberg had a significant (P < 0.05) increase in CD4+CD25- IL-2 mRNA transcription and IL-1ß transcription, the CD4+CD25- IL-2 mRNA transcription and IL-1ß transcription, were comparable to that in the control group at 11 and 32dpi identifying that the host inflammatory response against Salmonella disappears at 11 dpi. It can be concluded that S. Enteritidis and S. Heidelberg infection at 3 d of age induces a persistent infection through inducing T regulatory and altering the IL-10 mRNA transcription of T regulatory cells in chickens between 3 to 32 dpi and chickens become asymptomatic carriers of Salmonella after 18 dpi.