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Histamine derived from probiotic Lactobacillus reuteri suppresses TNF via modulation of PKA and ERK signaling.

Thomas CM, Hong T, van Pijkeren JP, Hemarajata P, Trinh DV, Hu W, Britton RA, Kalkum M, Versalovic J - PLoS ONE (2012)

Bottom Line: Previously, immunomodulatory factors secreted by L. reuteri ATCC PTA 6475 were unknown.A combined metabolomics and bacterial genetics strategy was utilized to identify small compound(s) produced by L. reuteri that were TNF-inhibitory.The identification of bacterial bioactive metabolites and their corresponding mechanisms of action with respect to immunomodulation may lead to improved anti-inflammatory strategies for chronic immune-mediated diseases.

View Article: PubMed Central - PubMed

Affiliation: Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America.

ABSTRACT
Beneficial microbes and probiotic species, such as Lactobacillus reuteri, produce biologically active compounds that can modulate host mucosal immunity. Previously, immunomodulatory factors secreted by L. reuteri ATCC PTA 6475 were unknown. A combined metabolomics and bacterial genetics strategy was utilized to identify small compound(s) produced by L. reuteri that were TNF-inhibitory. Hydrophilic interaction liquid chromatography-high performance liquid chromatography (HILIC-HPLC) separation isolated TNF-inhibitory compounds, and HILIC-HPLC fraction composition was determined by NMR and mass spectrometry analyses. Histamine was identified and quantified in TNF-inhibitory HILIC-HPLC fractions. Histamine is produced from L-histidine via histidine decarboxylase by some fermentative bacteria including lactobacilli. Targeted mutagenesis of each gene present in the histidine decarboxylase gene cluster in L. reuteri 6475 demonstrated the involvement of histidine decarboxylase pyruvoyl type A (hdcA), histidine/histamine antiporter (hdcP), and hdcB in production of the TNF-inhibitory factor. The mechanism of TNF inhibition by L. reuteri-derived histamine was investigated using Toll-like receptor 2 (TLR2)-activated human monocytoid cells. Bacterial histamine suppressed TNF production via activation of the H(2) receptor. Histamine from L. reuteri 6475 stimulated increased levels of cAMP, which inhibited downstream MEK/ERK MAPK signaling via protein kinase A (PKA) and resulted in suppression of TNF production by transcriptional regulation. In summary, a component of the gut microbiome, L. reuteri, is able to convert a dietary component, L-histidine, into an immunoregulatory signal, histamine, which suppresses pro-inflammatory TNF production. The identification of bacterial bioactive metabolites and their corresponding mechanisms of action with respect to immunomodulation may lead to improved anti-inflammatory strategies for chronic immune-mediated diseases.

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Stimulation of the H2 receptor inhibited the ERK signaling pathway.Immunoblot studies were performed to determine the effect of histamine on activation of the ERK signaling pathway. ERK was activated by phosphorylation on Thr202/Tyr204 (P-ERK). Treatment of TLR-stimulated THP-1 cells with L. reuteri 6475, histamine, or U0126 suppressed activation of ERK1/2, an effect that was significantly blocked in the presence of ranitidine. The β-actin antibody served as the protein loading control.
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pone-0031951-g007: Stimulation of the H2 receptor inhibited the ERK signaling pathway.Immunoblot studies were performed to determine the effect of histamine on activation of the ERK signaling pathway. ERK was activated by phosphorylation on Thr202/Tyr204 (P-ERK). Treatment of TLR-stimulated THP-1 cells with L. reuteri 6475, histamine, or U0126 suppressed activation of ERK1/2, an effect that was significantly blocked in the presence of ranitidine. The β-actin antibody served as the protein loading control.

Mentions: Previous studies demonstrated that PKA inhibits Ras/c-Raf activation of MEK/ERK MAPK signaling [23], [24]. Therefore, the phosphorylation states of MEK1/2 and ERK1/2 were examined by immunoblot to determine if histamine was, in fact, suppressing activation of the MEK/ERK signaling pathway. Treatment of activated THP-1 cells with L. reuteri 6475 CM, histamine or U0126, a specific chemical inhibitor of MEK activity which served as the positive control, blocked activation (phosphorylation) of both MEK1/2 and downstream ERK1/2 compared to the medium control (Figure 7 and Figure S6). Treatment with ranitidine partially restored activation of MEK1/2 and completely restored activation of ERK1/2 (Figure 7 and Figure S6), suggesting that inhibition of the MEK/ERK MAPK pathway occurred via H2 receptor activation. MEK1/2 and ERK1/2 protein quantities did not differ following these treatments. In summary, histamine derived from L. reuteri 6475 inhibited activation of MEK and downstream ERK, resulting in diminished TNF production by TLR2-stimulated monocytoid cells.


Histamine derived from probiotic Lactobacillus reuteri suppresses TNF via modulation of PKA and ERK signaling.

Thomas CM, Hong T, van Pijkeren JP, Hemarajata P, Trinh DV, Hu W, Britton RA, Kalkum M, Versalovic J - PLoS ONE (2012)

Stimulation of the H2 receptor inhibited the ERK signaling pathway.Immunoblot studies were performed to determine the effect of histamine on activation of the ERK signaling pathway. ERK was activated by phosphorylation on Thr202/Tyr204 (P-ERK). Treatment of TLR-stimulated THP-1 cells with L. reuteri 6475, histamine, or U0126 suppressed activation of ERK1/2, an effect that was significantly blocked in the presence of ranitidine. The β-actin antibody served as the protein loading control.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285189&req=5

pone-0031951-g007: Stimulation of the H2 receptor inhibited the ERK signaling pathway.Immunoblot studies were performed to determine the effect of histamine on activation of the ERK signaling pathway. ERK was activated by phosphorylation on Thr202/Tyr204 (P-ERK). Treatment of TLR-stimulated THP-1 cells with L. reuteri 6475, histamine, or U0126 suppressed activation of ERK1/2, an effect that was significantly blocked in the presence of ranitidine. The β-actin antibody served as the protein loading control.
Mentions: Previous studies demonstrated that PKA inhibits Ras/c-Raf activation of MEK/ERK MAPK signaling [23], [24]. Therefore, the phosphorylation states of MEK1/2 and ERK1/2 were examined by immunoblot to determine if histamine was, in fact, suppressing activation of the MEK/ERK signaling pathway. Treatment of activated THP-1 cells with L. reuteri 6475 CM, histamine or U0126, a specific chemical inhibitor of MEK activity which served as the positive control, blocked activation (phosphorylation) of both MEK1/2 and downstream ERK1/2 compared to the medium control (Figure 7 and Figure S6). Treatment with ranitidine partially restored activation of MEK1/2 and completely restored activation of ERK1/2 (Figure 7 and Figure S6), suggesting that inhibition of the MEK/ERK MAPK pathway occurred via H2 receptor activation. MEK1/2 and ERK1/2 protein quantities did not differ following these treatments. In summary, histamine derived from L. reuteri 6475 inhibited activation of MEK and downstream ERK, resulting in diminished TNF production by TLR2-stimulated monocytoid cells.

Bottom Line: Previously, immunomodulatory factors secreted by L. reuteri ATCC PTA 6475 were unknown.A combined metabolomics and bacterial genetics strategy was utilized to identify small compound(s) produced by L. reuteri that were TNF-inhibitory.The identification of bacterial bioactive metabolites and their corresponding mechanisms of action with respect to immunomodulation may lead to improved anti-inflammatory strategies for chronic immune-mediated diseases.

View Article: PubMed Central - PubMed

Affiliation: Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America.

ABSTRACT
Beneficial microbes and probiotic species, such as Lactobacillus reuteri, produce biologically active compounds that can modulate host mucosal immunity. Previously, immunomodulatory factors secreted by L. reuteri ATCC PTA 6475 were unknown. A combined metabolomics and bacterial genetics strategy was utilized to identify small compound(s) produced by L. reuteri that were TNF-inhibitory. Hydrophilic interaction liquid chromatography-high performance liquid chromatography (HILIC-HPLC) separation isolated TNF-inhibitory compounds, and HILIC-HPLC fraction composition was determined by NMR and mass spectrometry analyses. Histamine was identified and quantified in TNF-inhibitory HILIC-HPLC fractions. Histamine is produced from L-histidine via histidine decarboxylase by some fermentative bacteria including lactobacilli. Targeted mutagenesis of each gene present in the histidine decarboxylase gene cluster in L. reuteri 6475 demonstrated the involvement of histidine decarboxylase pyruvoyl type A (hdcA), histidine/histamine antiporter (hdcP), and hdcB in production of the TNF-inhibitory factor. The mechanism of TNF inhibition by L. reuteri-derived histamine was investigated using Toll-like receptor 2 (TLR2)-activated human monocytoid cells. Bacterial histamine suppressed TNF production via activation of the H(2) receptor. Histamine from L. reuteri 6475 stimulated increased levels of cAMP, which inhibited downstream MEK/ERK MAPK signaling via protein kinase A (PKA) and resulted in suppression of TNF production by transcriptional regulation. In summary, a component of the gut microbiome, L. reuteri, is able to convert a dietary component, L-histidine, into an immunoregulatory signal, histamine, which suppresses pro-inflammatory TNF production. The identification of bacterial bioactive metabolites and their corresponding mechanisms of action with respect to immunomodulation may lead to improved anti-inflammatory strategies for chronic immune-mediated diseases.

Show MeSH
Related in: MedlinePlus