• Journal of Microbiology and Biotechnology
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• 제32권5호
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• pp.638-644
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• 2022

Probiotics modulate the gut microbiota, which in turn regulate immune responses to maintain balanced immune homeostasis in the host. However, it is unclear how probiotic bacteria regulate immune responses. In this study we investigated the immunomodulatory effects of heat-killed probiotics, including Lactiplantibacillus plantarum KC3 (LP3), Lactiplantibacillus plantarum CKDB008 (LP8), and Limosilactobacillus fermentum SRK414 (LF4), via phagocytosis, nitric oxide (NO), and pro-inflammatory cytokine production in macrophages. We thus found that heat-killed LP8 could promote the clearance of foreign pathogens by enhancing the phagocytosis of macrophages. Treatment with heat-killed LP8 induced the production of NO and pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β. In addition, heat-killed LP8 suppressed the production of NO and cytokines in LPS-induced RAW264.7 cells, suggesting that heat-killed LP8 exerts immunomodulatory effects depending on the host condition. In sum, these results indicate that heat-killed LP8 possesses the potential for immune modulation while providing a molecular basis for the development of functional probiotics prepared from inactivated bacterial cells.

• Journal of Microbiology and Biotechnology
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• 제23권1호
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• pp.118-124
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• 2013

Vibrio parahaemolyticus in uncooked seafood causes acute gastroenteritis. The microorganism has two sets of type III secretion systems and two hemolysins. When it injects its effector proteins into a host cell via type III secretion system 1, one of the type III secretion systems induces secretion of interleukin (IL)-8, a proinflammatory chemokine, through the phosphorylation of ERK 1/2 and p38 MAPK. Although probiotics have beneficial effects on hosts and can help control some infectious diseases, there is little research on the efficacy of probiotics in V. parahaemolyticus infection. Here we pretreated V. parahaemolyticus-infected human intestinal epithelial cells with heat-killed Lactobacillus brevis KB290, a probiotic isolated from fermented vegetables (traditional Japanese pickles) and utilized as an ingredient of beverages and supplementary foods, and demonstrated its efficacy in enhancing IL-8 secretion from V. parahaemolyticus-infected cells. Among the three heat-killed lactic acid bacterial strains we tested, L. brevis KB290 induced the highest level of IL-8 secretions in the infected cells. Relative to control cells (Caco-2 cells pretreated with PBS), V. parahaemolyticus-infected Caco-2 cells pretreated with heat-killed L. brevis KB290 secreted IL-8 earlier, although concentrations were similar 450min after infection. Heat-killed L. brevis KB290 pretreatment also induced earlier ERK 1/2 phosphorylation, greater p38 MAPK phosphorylation, and enhanced IL-8 mRNA expression. Heat-killed L. brevis KB290 accelerated IL-8 secretion, a host cell immune response, in V. parahaemolyticus-infected cells. We consider this to be beneficial because IL-8 plays an important defensive role against infection, and would contribute to the repair of injured epithelial cells.

• Journal of Dairy Science and Biotechnology
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• 제38권2호
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• pp.112-120
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• 2020

본 연구는 Enterococcus faecalis EF-2001 사균체를 발효유에 첨가하였을 시 나타나는 생리활성을 검증하고자 실시하였다. 발효유는 같은 양의 starter만 넣은 일반발효유 NFM, E. faecalis EF-2001 사균체를 100 ㎍/mL의 농도로 첨가한 EFM1, E. faecalis EF-2001 사균체를 500 ㎍/mL의 농도로 넣은 EFM2를 제조하였다. E. faecalis EF-2001 사균체를 발효유 첨가하였을 때 나타나는 항염증 효과를 검증하기 위해 mouse 유래 대식세포인 RAW 264.7 cell을 이용하였다. RAW 264.7 cell을 이용한 세포독성 실험의 결과, 사균의 농도가 높아질수록 세포 생존율이 유의적으로 감소하였으며(p<0.05), 80% 이상의 세포 생존율을 가지는 농도인 5, 10, 15 ㎍/mL에서 실험을 진행하였다. Nitric oxide의 생성 억제능 측정결과는 LPS 처리군에 비해 발효유에서 NO 생성을 저해하는 경향을 나타냈다. 또한, 일반발효유보다 사균을 첨가한 발효유에서 NO 생성을 더욱 저해하는 결과를 나타내었다. Prostaglandin E₂의 억제율 측정결과도 15 ㎍/mL의 농도에서 PGE₂ 분비량을 감소시킴을 확인하였으며, 일반 발효유보다 사균이 첨가된 발효유에서 더욱 억제됨을 확인하였다. 따라서, 본 연구를 통해 E. faecalis EF-2001 사균체가 발효유에 첨가되어도 염증 매개물질인 NO 및 PGE₂의 생성을 감소시킴으로써 추후 사균체가 첨가된 발효유 제조 및 연구에 대한 기초 연구 결과로 활용될 수 있을 것으로 사료된다.

• Toxicological Research
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• 제29권2호
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• pp.129-135
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• 2013

Salmonella is one of the major pathogenic bacteria that cause food poisoning. This study investigated whether heat-killed as well as live Lactobacillus protects host animal against Salmonella infection. Live and heat-killed Lactobacillusacidophilus was administered orally to Sprague-Dawley rats for 2 weeks before the rats were inoculated with Salmonella. Rise in body temperature was moderate in the group that was treated with heat-killed bacteria as compared to the Salmonella control group. The mean amount of feed intake and water consumption of each rat in the heat-killed bacteria group were nearly normal. The number of fecal Salmonellae was comparable between the live and the heat-killed L. acidophilus groups. This finding shows that L. acidophilus facilitates the excretion of Salmonella. Moreover, the levels of pro inflammatory cytokines, including tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta, in the heat-killed L. acidophilus group were significantly lower when compared to the levels in the Salmonella control group. These results indicate that nonviable lactic acid bacteria also could play an important role in preventing infections by enteric pathogens such as Salmonella.

• Journal of Animal Science and Technology
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• 제63권3호
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• pp.520-530
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• 2021

This experiment was performed to verify whether dietary heat-killed Lactobacillus rhamnosus (LR) improves growth performance and modulates immune responses of weaned pigs. Ninety-six weaned pigs ([Landrace × Yorkshire] × Duroc; 6.95 ± 0.25 kg body weight [BW]; 28 d old) were randomly allocated to four treatments: 1) a basal diet without heat-killed LR (CON), 2) T1 (CON with 0.1% heat-killed LR), 3) T2 (CON with 0.2% heat-killed LR), and 4) T3 (CON with 0.4% heat-killed LR). Each treatment had six pens with four pigs (6 replicates per treatment) in a randomized completely block design. The heat-killed LR used in this study contained 1 × 10⁹ FU/g of LR in a commercial product. Pigs were fed each treatment for four weeks using a two-phase feeding program to measure growth performance and frequency of diarrhea. During the last week of this study, all diets contained 0.2% chromic oxide as an indigestible marker. Fecal sampling was performed through rectal palpation for the consecutive three days after the four adaptation days to measure apparent total tract digestibility (ATTD) of dry matter, crude protein, and gross energy (GE). Blood sampling was also performed on day 1, 3, 7, and 14 after weaning to measure immune responses such as serum tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), C-reactive protein (CRP), and cortisol. The heat-killed LR increased (p < 0.05) growth rate, feed efficiency, and ATTD of GE for overall experimental period compared with CON, but reduced (p < 0.05) post-weaning diarrhea. In addition, pigs fed diets contained heat-killed had lower concentrations of serum TNF-α (d 7; p < 0.05), TGF-β1 (d 7; p < 0.10), and cortisol (d 3 and 7; p < 0.05) than pigs fed CON. In conclusion, dietary heat-killed LR improved growth rate, modified immune responses of weaned pigs, and alleviated post-weaning diarrhea.

• 미생물학회지
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• 제51권3호
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• pp.241-248
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• 2015

프로바이오틱스에 대한 연구는 주로 생균의 효과가 많이 알려져 있지만 가열 처리된 유산균인 사균체의 기능에 대한 연구도 활발히 이루어지고 있다. 본 연구에서는 락토바실러스 아시도필러스 CBT LA1의 사균체의 장관장벽 기능에 대하여 in vitro, in vivo에서 실험하였다. 이를 위하여, 세포표면 소수성 상호작용력(cell surface hydrophobicity), 자가응집력(autoaggregation), 세포에 부착하는 능력(cell adhesion)과 자가응집력(autoaggregation), LPS와의 결합력을 조사하였다. 또한 HT-29 장상피세포에서 LPS로 유도되는 IL-8의 발현을 억제하는 효과를 조사하였다. CBT LA1을 80도에서 121도까지 10분 동안 열을 처리하였을 때, 80도에서 열을 처리한 CBT LA1 사균체가 가장 높은 세포에 부착하는 능력을 보여 주었다. CBT LA1 생균과 비교했을 때, 80도에서 열을 처리한 CBT LA1 사균체는 높은 LPS와의 결합력, 소수성 상호작용력, 자가응집력, HT-29 세포에 부착하는 능력과 IL-8의 발현을 억제하는 능력을 보여주었다. In vivo 실험에서 FITC로 label된 LPS를 투여하였을 때 16시간 후, CBT LA1 사균체를 섭취한 동물의 장관 내 LPS가 가장 많이 제거되었다. 이러한 연구 결과들은 CBT LA1 생균처럼 CBT LA1 사균체도 장관장벽 기능을 가지며 이는, 파마바이오틱스로서 그 가능성을 시사한다.

• Journal of Microbiology and Biotechnology
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• 제33권9호
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• pp.1189-1196
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• 2023

This study proposed to demonstrate the neuroprotective effects of heat-killed Levilactobacillus brevis KU15152. Heat-killed L. brevis KU15152 showed antioxidant activity similar to that of Lacticaseibacillus rhamnosus GG, in terms of radical scavenging activity. To evaluate the neuroprotective effects, conditioned medium (CM) obtained by incubating heat-killed bacteria in intestinal cells (HT-29) was used through gut-brain axis. CM from L. brevis KU15152 protected neuroblastoma cells (SH-SY5Y) against H₂O₂-induced oxidative stress. Pretreatment with CM significantly alleviated the morphological changes induced by H₂O₂. Heat-killed L. brevis KU15152 showed an increased brain-derived neurotrophic factor (BDNF) expression in HT-29 cells. L. brevis KU15152-CM remarkably downregulated the Bax/Bcl-2 ratio, while upregulating the expression of BDNF and tyrosine hydroxylase (TH) in SH-SY5Y cells. Furthermore, L. brevis KU15152-CM reduced caspase-3 activity following H₂O₂ treatment. In conclusion, L. brevis KU15152 can be potentially used as food materials to avoid neurodegenerative diseases.

• Journal of Dairy Science and Biotechnology
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• 제40권1호
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• pp.48-56
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• 2022

Enterococcus species have been reported to produce unique flavoring ingredients in fermented dairy products. Generally, they were found in cheese and fermented dairy products. Enterococcus spp. produce extracellular polysaccharides and reduce blood cholesterol levels in humans. This study used heat-killed E. faecalis and E. faecium in yogurt production to increase safety during consumption. The addition of heat-killed E. faecalis and E. faecium to milk did not affect the fermentation time of yogurt production, the growth of starter cultures, and the viscosity of yogurt. These results concluded that heat-killed Enterococcus, rather than live Enterococcus, is sufficiently possible and even safer to be added to milk products. Enterococcus species could be used as a safe and functional food additive to fermented milk products and supplements in health foods.

• Journal of Microbiology and Biotechnology
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• 제29권7호
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• pp.1022-1032
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• 2019

Probiotics are known to provide the host with immune-modulatory effects and are therefore of remarkable interest for therapeutic and prophylactic applications against various disorders, including inflammatory diseases. Weissella cibaria JW15 (JW15) has been reported to possess probiotic and antioxidant properties. However, the effect of JW15 on inflammatory responses has not yet been reported. Therefore, the objective of the current study was to evaluate the anti-inflammatory potential of JW15 against lipopolysaccharide (LPS) stimulation. The production of pro-inflammatory factors and the cellular signaling pathways following treatment with heat-killed JW15 was examined in LPS-induced RAW 264.7 cells. Treatment with heat-killed JW15 decreased nitric oxide and prostaglandin $E_2$ production via down-regulation of the inducible nitric oxide synthase and cyclooxygenase-2. In addition, treatment with heat-killed JW15 suppressed the expression of pro-inflammatory cytokines, interleukin $(IL)-1{\beta}$, IL-6, and tumor necrosis factor-${\alpha}$. The anti-inflammatory properties of treating with heat-killed JW15 were associated with mitogen-activated protein kinase signaling pathway-mediated suppression of nuclear factor-${\kappa}B$. These results indicated that JW15 possesses anti-inflammatory potential and provide a molecular basis regarding the development of functional probiotic products.

• Journal of Microbiology and Biotechnology
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• 제29권12호
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• pp.1894-1903
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• 2019

The purpose of this study was to determine the probiotic properties of Lactobacillus brevis KCCM 12203P isolated from the Korean traditional food kimchi and to evaluate the antioxidative activity and immune-stimulating potential of its heat-killed cells to improve their bio-functional activities. Lactobacillus rhamnosus GG, which is a representative commercial probiotic, was used as a comparative sample. Regarding probiotic properties, L. brevis KCCM 12203P was resistant to 0.3% pepsin with a pH of 2.5 for 3 h and 0.3% oxgall solution for 24 h, having approximately a 99% survival rate. It also showed strong adhesion activity (6.84%) onto HT-29 cells and did not produce β-glucuronidase but produced high quantities of leucine arylamidase, valine arylamidase, β-galactosidase, and N-acetyl-β-glucosaminidase. For antioxidant activity, it appeared that viable cells had higher radical scavenging activity in the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, while in the 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, heat-killed cells had higher antioxidant activity. Additionally, L. brevis KCCM 12203P showed higher lipid oxidation inhibition ability than L. rhamnosus GG; however, there was no significant difference (p < 0.05) between heat-killed cells and control cells. Furthermore, heat-killed L. brevis KCCM 12203P activated RAW 264.7 macrophage cells without cytotoxicity at a concentration lower than 10⁸ CFU/ml and promoted higher gene expression levels of inducible nitric oxide synthase, interleukin-1β, and interleukin-6 than L. rhamnosus GG. These results suggest that novel L. brevis KCCM 12203P could be used as a probiotic or applied to functional food processing and pharmaceutical fields for immunocompromised people.