• The Korea Journal of Herbology
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• v.37 no.5
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• pp.53-61
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• 2022

Objectives : The aim of this study was to investigate the effect of Baicalein (BA) on the production of hydrogen peroxide in lipoteichoic acid-stimulated RAW 264.7 mouse macrophages. Methods : Lipoteichoic acid-stressed RAW 264.7 mouse macrophages were incubated with baicalein at concentrations of 50 and 100 µM. Incubation time is 30 minutes, 2 h, 12 h, and 18 h. After incubation, The production of hydrogen peroxide in RAW 264.7 mouse macrophages was measured with dihydrorhodamine 123 assay. Streptococcus aureus lipoteichoic acid and Streptococcus pyogenes lipoteichoic acid were used as cell-stimulating lipoteichoic acid. Cell viabilities were measured with a modified MTT assay. Berberine, indomethacin, and gallic acid were incubated for the same time as the comparative materials. Results : BA at the concentration of 50 and 100 µM did not show cytotoxicity on RAW 264.7 mouse macrophages for 24 h incubation. For 30 minutes, 2 h, 12 h, and 18 h incubation, BA at the concentration of 50 and 100 µM significantly inhibited the production of hydrogen peroxide in RAW 264.7 mouse macrophages stimulated by Streptococcus aureus lipoteichoic acid (p < 0.05); also, BA at the concentration of 50 and 100 µM also inhibited the productions of hydrogen peroxide in RAW 264.7 mouse macrophages stimulated by Streptococcus pyogenes lipoteichoic acid significantly (p < 0.05). Conclusions : BA might have anti-bacterial activity related to its inhibition of hydrogen peroxide production in lipoteichoic acid-stimulated RAW 264.7 mouse macrophages.

• The Korea Journal of Herbology
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• v.38 no.4
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• pp.11-19
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• 2023

Objectives : The aim of this study was to investigate the effect of baicalein (BA) on the production of hydrogen peroxide and nitric oxide (NO) in RAW 264.7 mouse macrophages stimulated with polyinosinic-polycytidylic acid (poly-IC) and lipoteichoic acid. Methods : RAW 264.7 co-stimulated with poly-IC and lipoteichoic acid were incubated with baicalein at concentrations of 25 and 50 μM. Incubation time is 16 h, 18 h, 20 h, 22 h, and 24 h. After incubation, The production of hydrogen peroxide in RAW 264.7 was measured with dihydrorhodamine 123 assay. Chrysin was used as a comparative material. NO production was evaluated by griess assay. Results : For 16 h, 18 h, 20 h, 22 h, and 24 h incubation, BA at the concentration of 25 and 50 μM significantly inhibited the production of hydrogen peroxide in RAW 264.7 stimulated by poly-IC and lipoteichoic acid (p <0.001). In details, production of hydrogen peroxide in 'poly-IC and lipoteichoic acid'-stimulated RAW 264.7 treated for 16 h with BA at concentrations of 25 and 50 μM was 82.36% and 77.24% of the control group treated with poly-IC and lipoteichoic acid only, respectively; the production of hydrogen peroxide for 18 h was 83.15% and 77.91%, respectively;production of hydrogen peroxide for 20 h was 82.88% and 77.82%, respectively; production of hydrogen peroxide for 22 h was 83.27% and 78.17%, respectively; production of hydrogen peroxide for 24 h was 83.54% and 78.35%, respectively. Additionally, BA at the concentration of 50 and 100 μM significantly inhibited NO production in lipoteichoic acid-induced RAW 264.7 (p <0.001). Conclusions : BA might have anti-oxidative activity related to its inhibition of hydrogen peroxide production in 'poly-IC and lipoteichoic acid'-stimulated RAW 264.7 macrophages.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.652-659
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• 2021

Microorganism-derived compounds, such as peptidoglycan, lipoteichoic acid, and β-glucan were supplemented in the scuticociliate Miamiensis avidus (M. avidus) vaccine to verify the specify component contribution to the adjuvant effect. Vaccine was formulated with the inactivated M. avidus antigen (YS2, 4.44×10⁵ cells/fish) in combination with either peptidoglycan (10 ㎍ and 100 ㎍/fish), lipoteichoic acid (5 ㎍ and 50 ㎍/fish), or β-glucan (10 ㎍ and 100 ㎍/fish). Olive flounder injected with peptidoglycan supplemented vaccine (10 ㎍ and 100 ㎍/fish) exhibited significant protection, and the relative percent survival (RPS) was 55% and 65% at 4 weeks post vaccination (wpv), respectively, at the corresponding doses. The vaccine groups with added lipoteichoic acid (5 ㎍ and 50 ㎍/fish) exhibited RPS of 40% and 5%, respectively. Additionally, the group with added β-glucan (100 ㎍/fish) exhibited RPS of 35%, but no effect was observed in the group with added 10 ㎍/fish β-glucan. At 8 wpv, olive flounder injected with peptidoglycan and lipoteichoic acid supplemented vaccines exhibited protection with RPS range of 11/11% and 5/21%, respectively, at the respective doses. M. avidus vaccine containing 10 ㎍ and 100 ㎍/fish of β-glucan exhibited the RPS of 32% and 37%, respectively. Conclusively, peptidoglycan contributed in high protection of the M. avidus vaccine, and thus, it can be used as an effective adjuvant in the M. avidus vaccine.

• Microbiology and Biotechnology Letters
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• v.50 no.2
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• pp.293-300
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• 2022

Lipoteichoic acid (LTA) regulates the immune system, including inflammatory responses, through TLR2-mediated signaling pathways. LTA isolated from Staphylococcus aureus (aLTA) has been shown to induce apoptosis, but the detailed mechanism has not been identified. We found that aLTA induced apoptosis through an autocrine mechanism in the human monocyte-like cell line, THP-1. We observed that the expression level of the anti-apoptosis protein, Bcl2, was suppressed in LTA-treated THP-1 cells. In addition, the cytokines, TNF-α and IFN-γ, which have been shown to induce apoptosis in some cell lines, were involved in THP-1 cell death via the modulation of Bcl2. The suppression of Bcl2 by aLTA was recovered when the negative regulator, SOCS-1, was knocked down. Taken together, these results showed that aLTA induced apoptosis in THP-1 cells through an autocrine mechanism of cytokines and SOCS-1-mediated Bcl2 inhibition.

• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1051-1058
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• 2014

Platelet-activating factor receptor (PAFR) plays an important role in bacterial infection and inflammation. We examined the effect of the bacterial cell wall components lipopolysaccharide (LPS) and lipoteichoic acid (LTA) from Lactobacillus plantarum (pLTA) and Staphylococcus aureus (aLTA) on PAFR expression in THP-1, a monocyte-like cell line. LPS and aLTA, but not pLTA, significantly increased PAFR expression, whereas priming with pLTA inhibited LPS-mediated or aLTA-mediated PAFR expression. Expression of Toll-like receptor (TLR) 2 and 4, and CD14 increased with LPS and aLTA treatments, but was inhibited by pLTA pretreatment. Neutralizing antibodies against TLR2, TLR4, and CD14 showed that these receptors were important in LPS-mediated or aLTA-mediated PAFR expression. PAFR expression is mainly regulated by the nuclear factor kappa B signaling pathway. Blocking PAF binding to PAFR using a PAFR inhibitor indicated that LPS-mediated or aLTA-mediated PAF expression affected TNF-${\alpha}$ production. In the mouse small intestine, pLTA inhibited PAFR, TLR2, and TLR4 expression that was induced by heat-labile toxin. Our data suggested that pLTA has an anti-inflammatory effect by inhibiting the expression of PAFR that was induced by pathogenic ligands.

• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1310-1317
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• 2018

The stems of Dendrobium moniliforme have been used in traditional herbal medicine for the treatment of fever and lack of body fluid in Korea. In this study, we investigated anti-inflammatory effects of the aqueous extract of D. moniliforme stems (DM) in response to lipoteichoic acid (LTA), a major constituent of the cell wall of Gram-positive bacteria. DM inhibited LTA-induced expression of a pro-inflammatory mediator inducible nitric oxide synthase (iNOS) in the murine macrophages. And DM induced expression of heme oxygenase-1 (HO-1) at the transcriptional level. Conversely, the knockdown of HO-1 expression by siRNA markedly reversed the inhibitory effects of DM on LTA-induced iNOS expression. We also demonstrated that nuclear translocation of Nrf2 was increased following treatment with DM. In addition, DM-mediated Nrf2 activation and HO-1 expression were suppressed by PI3K/Akt and p38 inhibitors; treatment with DM also resulted in phosphorylation of Akt and p38. These results suggest that DM inhibits the expression of iNOS in LTA-stimulated macrophages, and that these effects are mediated by the upregulation of HO-1 expression via PI3K/Akt/p38-Nrf2 signaling.

• Journal of Microbiology and Biotechnology
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• v.26 no.7
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• pp.1198-1205
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• 2016

Lactic acid bacteria (LAB) have beneficial effects on intestinal health and skin diseases. Lipoteichoic acid (LTA), a cell wall component of gram-positive bacteria, is known to induce the production of several cytokines such as TNF-α, IL-1β, and IL-8 and affect the intestinal microflora, anti-aging, sepsis, and cholesterol level. In this study, Weissella cibaria was isolated from Indian dairy products, and we examined its immune-enhancing effects. Live and heat-killed W. cibaria did not induce the secretion of immune-related cytokines, whereas LTA isolated from W. cibaria (cLTA) significantly increased the secretion of TNF-α, IL-1β, and IL-6 in a dose-dependent manner. cLTA increased the phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells, p38 mitogen-activated protein kinases, and c-Jun N-terminal kinases in THP-1 cells. The secretion of TNF-α and IL-6 was also increased in the cLTA-treated mouse splenocytes. These results suggest that cLTA, but not W. cibaria whole cells, has immune-boosting potential and can be used to treat immunosuppression diseases.

• Journal of Microbiology and Biotechnology
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• v.27 no.10
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• pp.1820-1826
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• 2017

Lipoteichoic acid (LTA), a cell wall component of gram-positive bacteria, is recognized by Toll-like receptor 2, expressed on certain mammalian cell surfaces, initiating signaling cascades that include nuclear factor kappa-light-chain-enhancer of activated B cells (NF-${\kappa}B$) and mitogen-activated protein kinase. There are many structural and functional varieties of LTA, which vary according to the different species of gram-positive bacteria that produce them. In this study, we examined whether LTA isolated from Staphylococcus aureus (aLTA) affects the expression of junction proteins in keratinocytes. In HaCaT cells, tight junction-related gene expression was not affected by aLTA, whereas adherens junction-related gene expression was modified. High doses of aLTA induced the phosphorylation of extracellular signal-regulated protein kinases 1 and 2, which in turn induced the epithelial-mesenchymal transition (EMT) of HaCaT cells. When cells were given a low dose of aLTA, however, NF-${\kappa}B$ was activated and the total cell population increased. Taken together, our study suggests that LTA from S. aureus infections in the skin may contribute both to the outbreak of EMT-mediated carcinogenesis and to the genesis of wound healing in a dose-dependent manner.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1191-1196
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• 2008

Staphylococcus aureus is a common etiologic agent for Gram-positive sepsis, and its lipoteichoic acid (LTA) may be important in causing Gram-positive bacterial septic shock. Here, we demonstrate that highly purified LTA (pLTA) isolated from Lactobacillus plantarum inhibited S. aureus LTA (aLTA)-induced TNF-${\alpha}$ production in THP-1 cells. Whereas pLTA scarcely induced TNF-${\alpha}$ production, aLTA induced excessive TNF-${\alpha}$ production. Interestingly, aLTA-induced TNF-${\alpha}$ production was inhibited by pLTA pretreatment. Compared with pLTA, aLTA induced a strong signal transduction through the MyD88, NF-${\kappa}B$, and MAP kinases. This signaling, however, was reduced by a pLTA pretreatment, and resulted in the inhibition of aLTA-induced TNF-${\alpha}$ production. Whereas dealanylated LTAs, as well as native LTAs, contributed to TNF-${\alpha}$ induction or TNF-${\alpha}$ reduction, deacylated LTAs did not, indicating that the acyl chain of LTA played an important role in the LTA-mediated immune regulation. These results suggest that pLTA may act as an antagonist for aLTA, and that an antagonistic pLTA may be a useful agent for suppressing the septic shock caused by Gram-positive bacteria.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.1023-1030
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• 2013

Lipoteichoic acid (LTA), uniquely expressed on gram-positive bacteria, is recognized by Toll-like receptor 2 (TLR2) on not only antigen-presenting cells but also activated T cells. Therefore, it is reasonable to assume that LTA is acting on T cells. However, little is known about the effect of LTA on T-cell regulation. In the present study, we investigated the immunomodulatory effects of LTA on $CD4^+$ T cells. Effector $CD4^+$ T cells, induced after co-culture with S. aureus-pulsed dendritic cells, produced high levels of interferon-${\gamma}$, CD25, CD69, and TLRs 2 and 4. When effector $CD4^+$ T cells were treated with LTA, the expressions of the membrane-bound form of transforming growth factor (TGF)-${\beta}$ and forkhead box P3 increased. Coincidently, the proliferation of effector $CD4^+$ T cells was declined after LTA treatment. When TGF-${\beta}$ signaling was blocked by the TGF-${\beta}$ receptor 1 kinase inhibitor, LTA failed to suppress the proliferation of effector $CD4^+$ T cells. Therefore, the present results suggest that LTA suppresses the activity of effector $CD4^+$ T cells by enhancing TGF-${\beta}$ production.