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Aeromonas salmonicida Infection Only Moderately Regulates Expression of Factors Contributing to Toll-Like Receptor Signaling but Massively Activates the Cellular and Humoral Branches of Innate Immunity in Rainbow Trout (Oncorhynchus mykiss).

Brietzke A, Korytář T, Jaros J, Köllner B, Goldammer T, Seyfert HM, Rebl A - J Immunol Res (2015)

Bottom Line: In contrast, only the fish-specific tlr22a2 and the downstream factor irak1 featured clearly increased transcript levels, while the mRNA concentrations of many other tlr genes decreased.In conclusion, no specific TLR can be singled out as a dominant receptor for A. salmonicida.The recruitment of cellular factors of innate immunity rather than induced expression of pathogen receptors is hence of key importance for mounting a first immune defense against invading A. salmonicida.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.

ABSTRACT
Toll-like receptors (TLRs) are known to detect a defined spectrum of microbial structures. However, the knowledge about the specificity of teleost Tlr factors for distinct pathogens is limited so far. We measured baseline expression profiles of 18 tlr genes and associated signaling factors in four immune-relevant tissues of rainbow trout Oncorhynchus mykiss. Intraperitoneal injection of a lethal dose of Aeromonas salmonicida subsp. salmonicida induced highly increased levels of cytokine mRNAs during a 72-hour postinfection (hpi) period. In contrast, only the fish-specific tlr22a2 and the downstream factor irak1 featured clearly increased transcript levels, while the mRNA concentrations of many other tlr genes decreased. Flow cytometry quantified cell trafficking after infection indicating a dramatic influx of myeloid cells into the peritoneum and a belated low level immigration of lymphoid cells. T and B lymphocytes were differentiated with RT-qPCR revealing that B lymphocytes emigrated from and T lymphocytes immigrated into head kidney. In conclusion, no specific TLR can be singled out as a dominant receptor for A. salmonicida. The recruitment of cellular factors of innate immunity rather than induced expression of pathogen receptors is hence of key importance for mounting a first immune defense against invading A. salmonicida.

No MeSH data available.


Related in: MedlinePlus

Copy number of (a) PRRs and (b) downstream signaling factors in selected tissues from healthy trout. Quantitative RT-PCR was used to determine the number of transcripts/μg total RNA (ordinate) in spleen (dashed bars), head kidney (filled bars), liver (open bars), and thymus (chequered bars) of five healthy rainbow trout. Bars indicate mean ± SEM.
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fig2: Copy number of (a) PRRs and (b) downstream signaling factors in selected tissues from healthy trout. Quantitative RT-PCR was used to determine the number of transcripts/μg total RNA (ordinate) in spleen (dashed bars), head kidney (filled bars), liver (open bars), and thymus (chequered bars) of five healthy rainbow trout. Bars indicate mean ± SEM.

Mentions: We performed a quantitative real-time PCR (RT-qPCR) profiling across 19 factors constituting the recognition of MAMPs in rainbow trout. Regarding the tissue-specific expression, we found that all 13 tlr genes were significantly expressed in spleen, head kidney, liver, and thymus (Figure 2(a)). However, we observed large differences in basal levels of tlr transcripts. Spleen tissue featured the highest mRNA concentrations of almost all the Tlr-encoding genes, as frequently found in other fish species [26]. The copy numbers ranged from a minimum of 0.12 ± 0.02 × 106 (tlr5) to a maximum of 1.3 ± 0.18 × 106 copies (tlr21) per μg RNA. The concentrations in head kidney amounted to approximately one-third of the values found in spleen with tlr5 featuring the lowest abundance of only 7% of the level in spleen. Levels in liver were generally much lower than in spleen, amounting for eleven of the considered tlr genes on average to less than 10% of the levels as recorded in spleen. Yet, tlr5 and tlr3 were found to be exceptional since their mRNA concentrations reached 163% and 58% of those values measured in spleen.


Aeromonas salmonicida Infection Only Moderately Regulates Expression of Factors Contributing to Toll-Like Receptor Signaling but Massively Activates the Cellular and Humoral Branches of Innate Immunity in Rainbow Trout (Oncorhynchus mykiss).

Brietzke A, Korytář T, Jaros J, Köllner B, Goldammer T, Seyfert HM, Rebl A - J Immunol Res (2015)

Copy number of (a) PRRs and (b) downstream signaling factors in selected tissues from healthy trout. Quantitative RT-PCR was used to determine the number of transcripts/μg total RNA (ordinate) in spleen (dashed bars), head kidney (filled bars), liver (open bars), and thymus (chequered bars) of five healthy rainbow trout. Bars indicate mean ± SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4525466&req=5

fig2: Copy number of (a) PRRs and (b) downstream signaling factors in selected tissues from healthy trout. Quantitative RT-PCR was used to determine the number of transcripts/μg total RNA (ordinate) in spleen (dashed bars), head kidney (filled bars), liver (open bars), and thymus (chequered bars) of five healthy rainbow trout. Bars indicate mean ± SEM.
Mentions: We performed a quantitative real-time PCR (RT-qPCR) profiling across 19 factors constituting the recognition of MAMPs in rainbow trout. Regarding the tissue-specific expression, we found that all 13 tlr genes were significantly expressed in spleen, head kidney, liver, and thymus (Figure 2(a)). However, we observed large differences in basal levels of tlr transcripts. Spleen tissue featured the highest mRNA concentrations of almost all the Tlr-encoding genes, as frequently found in other fish species [26]. The copy numbers ranged from a minimum of 0.12 ± 0.02 × 106 (tlr5) to a maximum of 1.3 ± 0.18 × 106 copies (tlr21) per μg RNA. The concentrations in head kidney amounted to approximately one-third of the values found in spleen with tlr5 featuring the lowest abundance of only 7% of the level in spleen. Levels in liver were generally much lower than in spleen, amounting for eleven of the considered tlr genes on average to less than 10% of the levels as recorded in spleen. Yet, tlr5 and tlr3 were found to be exceptional since their mRNA concentrations reached 163% and 58% of those values measured in spleen.

Bottom Line: In contrast, only the fish-specific tlr22a2 and the downstream factor irak1 featured clearly increased transcript levels, while the mRNA concentrations of many other tlr genes decreased.In conclusion, no specific TLR can be singled out as a dominant receptor for A. salmonicida.The recruitment of cellular factors of innate immunity rather than induced expression of pathogen receptors is hence of key importance for mounting a first immune defense against invading A. salmonicida.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.

ABSTRACT
Toll-like receptors (TLRs) are known to detect a defined spectrum of microbial structures. However, the knowledge about the specificity of teleost Tlr factors for distinct pathogens is limited so far. We measured baseline expression profiles of 18 tlr genes and associated signaling factors in four immune-relevant tissues of rainbow trout Oncorhynchus mykiss. Intraperitoneal injection of a lethal dose of Aeromonas salmonicida subsp. salmonicida induced highly increased levels of cytokine mRNAs during a 72-hour postinfection (hpi) period. In contrast, only the fish-specific tlr22a2 and the downstream factor irak1 featured clearly increased transcript levels, while the mRNA concentrations of many other tlr genes decreased. Flow cytometry quantified cell trafficking after infection indicating a dramatic influx of myeloid cells into the peritoneum and a belated low level immigration of lymphoid cells. T and B lymphocytes were differentiated with RT-qPCR revealing that B lymphocytes emigrated from and T lymphocytes immigrated into head kidney. In conclusion, no specific TLR can be singled out as a dominant receptor for A. salmonicida. The recruitment of cellular factors of innate immunity rather than induced expression of pathogen receptors is hence of key importance for mounting a first immune defense against invading A. salmonicida.

No MeSH data available.


Related in: MedlinePlus