• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.786-790
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• 2006

Cellular components of Lactococcus lactis ssp. lactis (heat-killed whole cells, cytoplasm, and cell walls) were tested for their in vivo immunopotentiating activity. Peritoneal macrophages from mice orally administered with heat-killed whole cells exhibited significantly greater phagocytic activity than the groups administered with cell-wall fraction or cytoplasm fraction. The cytotoxicity of natural-killer cells was the highest in the group administered with whole cells, and the production of cytokines ($IFN-\gamma$, IL-2, and IL-12) in spleen cells was significantly higher, when cellular components were injected, and it tended to be higher in the cell-wall and cytoplasm groups than in the whole-cell group. Interestingly, the cytokine production of Peyer's patch cells was high, when cytoplasm fractions were administered. These results demonstrate that whole cells and cytoplasm and cell-wall fractions of L. lactis ssp. lactis have immunopotentiating activities, which are related to the stimulation of Peyer's patches.

• Journal of Microbiology and Biotechnology
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• v.13 no.2
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• pp.202-206
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• 2003

To determine the effect of immunopotentiating activity of cellular components of Lactococcus lactis ssp. lactis, the immune function was analyzed in vitro using mice cells. When stimulated with mitogens, productions of $IFN-{\gamma}$, IL-12, $TNF-{\alpha}$, and IL-6 were enhanced in spleen cells treated with cellular components, with IL-4 production being the highest in spleen cells treated with cytoplasm fraction. Without mitogen stimulation, the productions of $IFN-{\gamma}$ and IL-12 were the highest in spleen cells treated with heat-killed whole cell. $TNF-{\alpha}$ and IL-6 productions were also high in spleen cells treated with all cellular components. Only heat-killed whole cell showed significant enhancement in natural killer cell activity. In peritoneal exudates cells, $TNF-{\alpha}$ production was enhanced significantly by all cellular components of Lactococcus lactis ssp. lactis These results indicate that the cellular components of Lactococcus lactis ssp. lactis are capable of stimulating immune cells to produce cytokines, and that both their cell walls and cytoplasm fraction contribute to these capacities.

• Parasites, Hosts and Diseases
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• v.51 no.1
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• pp.85-92
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• 2013

IL-23 and IL-12 are structurally similar and critical for the generation of efficient cellular immune responses. Toxoplasma gondii induces a strong cell-mediated immune response. However, little is known about IL-23 secretion profiles in T. gondii-infected immune cells in connection with IL-12. We compared the patterns of IL-23 and IL-12 production by THP-1 human monocytic cells in response to stimulation with live or heat-killed T. gondii tachyzoites, or with equivalent quantities of either T. gondii excretory/secretory proteins (ESP) or soluble tachyzoite antigen (STAg). IL-23 and IL-12 were significantly increased from 6 hr after stimulation with T. gondii antigens, and their secretions were increased with parasite dose-dependent manner. IL-23 concentrations were significantly higher than those of IL-12 at the same multiplicity of infection. IL-23 secretion induced by live parasites was significantly higher than that by heat-killed parasites, ESP, or STAg, whereas IL-12 secretion by live parasite was similar to those of ESP or STAg. However, the lowest levels of both cytokines were at stimulation with heat-killed parasites. These data indicate that IL-23 secretion patterns by stimulation with various kinds of T. gondii antigens at THP-1 monocytic cells are similar to those of IL-12, even though the levels of IL-23 induction were significantly higher than those of IL-12. The detailed kinetics induced by each T. gondii antigen were different from each other.

• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1248-1254
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• 2019

Identification of novel probiotic strains is of great interest in the field of functional foods. Specific strains of heat-killed bacteria have been reported to exert immunomodulatory effects. Herein, we investigated the immune-stimulatory function of heat-killed Lactobacillus plantarum KCTC 13314BP (LBP). Treatment with LBP significantly increased the production of $TNF-{\alpha}$ and IL-6 by macrophages. More importantly, LBP was able to enhance the phagocytic activity of macrophages against bacterial particles. Activation of p38, JNK, ERK, $NF-{\kappa}B$, and STAT3 was involved in the immunomodulatory function of LBP. LBP treatment significantly increased production of $TNF-{\alpha}$ by bone marrow-derived macrophages and splenocytes, further confirming the immunostimulatory effect of LBP in primary immune cells. Interestingly, the immunomodulatory effects of LBP were much stronger than those of Lactobacillus rhamnosus GG, a well-known probiotic strain. These results indicate that LBP can be a promising immune-enhancing functional food agent.

• IMMUNE NETWORK
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• v.13 no.5
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• pp.205-212
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• 2013

Dectin-1, which specifically recognizes ${\beta}$-glucan of fungal cell walls, is a non-Toll-like receptor (TLR) pattern recognition receptor and a representative of C-type lectin receptors (CLRs). The importance of Dectin-1 in innate immune cells, such as dendritic cells and macrophages, has previously been well studied. However, the function of Dectin-1 in B cells is very poorly understood. To determine the role of Dectin-1 in B cell activation, we first investigated whether mouse B cells express Dectin-1 and then assessed the effect of Dectin-1 stimulation on B cell proliferation and antibody production. Mouse B cells express mRNAs encoding CLRs, including Dectin-1, and surface Dectin-1 was expressed in B cells of C57BL/6 rather than BALB/c strain. Dectin-1 agonists, heat-killed Candida albicans (HKCA) and heat-killed Saccharomyces cerevisiae (HKSC), alone induced B cell proliferation but not antibody production. Interestingly, HKSC, HKCA, and depleted zymosan (a selective Dectin-1 agonist) selectively enhanced LPS-driven IgG1 production. Taken together, these results suggest that, during fungal infection, ${\beta}$-glucan-stimulated Dectin-1 may cooperate with TLR4 to specifically enhance IgG1 production by mouse B cells.

• Journal of Microbiology and Biotechnology
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• v.30 no.6
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• pp.926-929
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• 2020

This study aimed to determine the immune-stimulating effects of heat-killed Lactobacillus plantarum Ln1 (HK-Ln1) through the production of nitric oxide (NO) and pro-inflammatory cytokine achieved by inducing NF-κB and mitogen-activated protein kinase (MAPK)-signaling pathways in macrophages. HK-Ln1 showed higher NO and cytokine production compared to control (nonstimulated lipopolysaccharide); in addition, the expression of inducible nitric oxide synthase (iNOS) was induced through HK-Ln1treatment. The phosphorylation of IκB-α and p65 increased following treatment by HK-Ln1, which implicates IκB-α degradation and the translocation of p65 to nucleus. In addition, the phosphorylation of MAPKs, ERK 1/2, JNK, and p38 was induced following HK-Ln1 treatment.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1010-1016
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• 2006

The effects of the cell viability and integrity of Bifidobacterium on suppression of allergy were investigated. C3H/HeJ mice were sensitized on weeks 3, 4, 6, and 8 with ovalbumin and choleratoxin to induce an allergic reaction. Mice fed 0.2% of live, disrupted, or heat-killed Bifidobacterium bifidum BGN4 in the pellets of their diet for 8 weeks starting 2 weeks before initial sensitization differentially suppressed the allergy response in terms of levels of IgE and IgG1 in their sera, and symptoms on their tails. Viable Bifidobacterium was more effective than disrupted or heat-killed cells in suppressing the allergy. Growth inhibition, which occurred in the sham group at week 4, did not occur in the treated groups. These results show that Bifidobacterium has a suppressive effect on the allergic response of mice, and that the viability and integrity of the Bifidobacterium is required for effective suppression in our experimental model.

• Journal of Microbiology and Biotechnology
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• v.34 no.7
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• pp.1491-1500
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• 2024

Inflammation is a biodefense mechanism that provides protection against painful conditions such as inflammatory bowel disease, other gastrointestinal problems, and irritable bowel syndrome. Paraprobiotics have probiotic characteristics of intestinal modulation along with merits of safety and stability. In this study, heat-killed Lactiplantibacillus plantarum KU15122 (KU15122) was investigated for its anti-inflammatory properties. KU15122 was subjected to heat-killed treatment for enhancement of its safety, and its concentration was set at 8 log CFU/mL for conducting different experiments. Nitric oxide production was most remarkably reduced in the KU15122 group, whereas it was increased in the LPS-treated group. In RAW 264.7 cells, KU15122 inhibited the expression of inducible nitric oxide synthase, cyclooxygenase-2, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. ELISA revealed that among the tested strains, KU15122 exhibited the most significant reduction in PGE2, IL-1β, and IL-6. Moreover, KU15122 inhibited various factors involved in the nuclear factor-kappa B, activator protein-1, and mitogen-activated protein kinase pathways. In addition, KU15122 reduced the generation of reactive oxygen species. The anti-inflammatory effect of KU15122 was likely attributable to the bacterial exopolysaccharides. Conclusively, KU15122 exhibits anti-inflammatory potential against inflammatory diseases.

• Journal of Dairy Science and Biotechnology
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• v.38 no.2
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• pp.112-120
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• 2020

This study was conducted to verify the physiological activity of heat-killed Enterococcus faecalis EF-2001 probiotics in fermented milk. The anti-inflammatory effects of fermented milk supplemented with different concentrations (0, 100, and 500 ㎍/mL) of E. faecalis EF-2001 were determined using MTT assay and nitric oxide inhibition assay. The MTT assay was performed using RAW 264.7 cells. Results revealed that the rates of cytotoxicity and cell survival decreased significantly with increase in the concentration of heat-killed probiotics (p<0.05). Moreover, fermented milk supplemented with 100 ㎍/mL EF-2001 (EFM1) and the fermented milk supplemented with 500 ㎍/mL EF-2001 (EFM2) exhibited higher nitric oxide inhibition than normal fermented milk (NFM). Additionally, EFM2 significantly reduced the ratio of prostaglandin E₂ compared to NFM (p<0.05). In conclusion, the treatment sample showed higher anti-inflammatory activity than NFM. The findings of this study could be used as a basic guideline for manufacturing of NFM supplemented with heat-killed probiotics.

• Journal of Microbiology and Biotechnology
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• v.30 no.9
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• pp.1395-1403
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• 2020

There is an increasing interest in using inactivated probiotics to modulate the host immune system and protect against pathogens. As the immunomodulatory function of heat-killed Lactobacillus brevis KCTC 12777BP (LBB) and its mechanism is unclear, we investigated the effect of LBB on immune response based on the hypothesis that LBB might exert stimulatory effects on immunity. In the current study, we demonstrate that administration of LBB can exert immune-stimulatory effects and promote clearance of foreign matters through enhancing phagocytosis. Treatment with LBB induced the production of TNF-α, IL-6, and nitric oxide in macrophages. Importantly, LBB directly increased the phagocytic activity of macrophages against bacterial particles. LBB was able to promote the production of TNF-α in bone marrow-derived macrophages and splenocytes and also increase the proliferation rate of splenocytes, suggesting that the immune-stimulating activity of LBB can be observed in primary immune cells. Investigation into the molecular mechanism responsible revealed that LBB upregulates TAK1 activity and its downstream ERK, p38, and JNK signaling pathways. To further confirm the immunomodulatory capability of LBB in vivo, we orally administered LBB to mice and assessed the effect on primary splenocytes. Splenocytes isolated from LBB-treated mice exhibited higher TNF-α expression and proliferative capacity. These results show that heat-killed L. brevis, a wildly consumed probiotic, may provide protection against pathogens through enhancing host immunity.