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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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Quantification of histamine by triple quadrupole mass spectrometry.Histamine in HILIC-HPLC fractions B2–B7 from L. reuteri 6475 grown in a glucose-containing medium was quantified by triple quadrupole mass spectrometry. The y-axis indicates TNF production from activated human monocytoid cells. The concentration of histamine (pg/µL) is indicated above each bar graph. Elevated levels of histamine correlated with TNF inhibition.
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pone-0031951-g003: Quantification of histamine by triple quadrupole mass spectrometry.Histamine in HILIC-HPLC fractions B2–B7 from L. reuteri 6475 grown in a glucose-containing medium was quantified by triple quadrupole mass spectrometry. The y-axis indicates TNF production from activated human monocytoid cells. The concentration of histamine (pg/µL) is indicated above each bar graph. Elevated levels of histamine correlated with TNF inhibition.

Mentions: Triple quadrupole mass spectrometry is an established method of quantifying small molecular compounds [28]. This method was used to quantify histamine in a restricted set of HILIC-HPLC fractions from aqueous TFA-treated cell pellets of L. reuteri 6475 grown in LDMIIIG. The standard curve used to quantify histamine is shown in Figure S2. All TNF-inhibitory HILIC-HPLC fractions (B3, B5, and B6) contained elevated concentrations of histamine (>500 pg/µL), while non-TNF-inhibitory HILIC-HPLC fractions contained less than 200 pg/µL histamine (Figure 3). The “gap” in immunomodulatory activity at fraction B4 correlated with low histamine content when compared to the neighboring fractions B3, B5, and B6. It is not entirely clear why histamine eluted in two peaks from the HILIC-HPLC column. The supernatant from liquid cultures of L. reuteri 6475 grown in LDMIIIG contained measurable quantities of histamine (approximately 300 pg/mL), whereas the culture supernatant of the same strain grown in LDMIIIS had minimal amounts of histamine (Figure 2D).


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)

Quantification of histamine by triple quadrupole mass spectrometry.Histamine in HILIC-HPLC fractions B2–B7 from L. reuteri 6475 grown in a glucose-containing medium was quantified by triple quadrupole mass spectrometry. The y-axis indicates TNF production from activated human monocytoid cells. The concentration of histamine (pg/µL) is indicated above each bar graph. Elevated levels of histamine correlated with TNF inhibition.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0031951-g003: Quantification of histamine by triple quadrupole mass spectrometry.Histamine in HILIC-HPLC fractions B2–B7 from L. reuteri 6475 grown in a glucose-containing medium was quantified by triple quadrupole mass spectrometry. The y-axis indicates TNF production from activated human monocytoid cells. The concentration of histamine (pg/µL) is indicated above each bar graph. Elevated levels of histamine correlated with TNF inhibition.
Mentions: Triple quadrupole mass spectrometry is an established method of quantifying small molecular compounds [28]. This method was used to quantify histamine in a restricted set of HILIC-HPLC fractions from aqueous TFA-treated cell pellets of L. reuteri 6475 grown in LDMIIIG. The standard curve used to quantify histamine is shown in Figure S2. All TNF-inhibitory HILIC-HPLC fractions (B3, B5, and B6) contained elevated concentrations of histamine (>500 pg/µL), while non-TNF-inhibitory HILIC-HPLC fractions contained less than 200 pg/µL histamine (Figure 3). The “gap” in immunomodulatory activity at fraction B4 correlated with low histamine content when compared to the neighboring fractions B3, B5, and B6. It is not entirely clear why histamine eluted in two peaks from the HILIC-HPLC column. The supernatant from liquid cultures of L. reuteri 6475 grown in LDMIIIG contained measurable quantities of histamine (approximately 300 pg/mL), whereas the culture supernatant of the same strain grown in LDMIIIS had minimal amounts of histamine (Figure 2D).

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