Inhibitory effect of oral administration of Lactobacillus casei on 3-methylcholanthrene-induced carcinogenesis in mice

The present study was designed to determine whether tumor induction by 3-methylcholanthrene (MC), a carcinogenic hydrocarbon, can be inhibited by oral administration of Lactobacillus casei strain Shirota (LC). C3H/HeN mice were divided into four groups and assigned to the following treatments: treated with MC and given control or LC-containing diet; treated with vehicle only and given control or LC-containing diet. MC (1 mg) was injected intradermally at 7 weeks of age and the tumor incidence was monitored; LC was mixed into a diet at a concentration of 0.05% (w/w) and the diet was fed from the day of MC injection throughout the study. Spleen cells were analyzed for the immune parameters at 12 and 16 weeks after the MC injection. Oral feeding of mice with LC reduced tumor incidence (P < 0.05). MC treatment lowered the in vitro response to concanavalin A (Con A) of spleen cells, the secretion of interleukin-2 in spleen cell culture after stimulation of the cells with Con A and the proportions of CD3⁺, CD4⁺ and CD8⁺ splenic cells. However, the analysis of the spleen cells obtained from the mice treated with MC and given the LC-containing diet revealed that these disrupted host immune parameters were maintained at the level of normal controls. These results suggest that oral feeding of mice with LC inhibits MC-induced tumorigenesis by modulating the disrupted host immune responses during MC carcinogenesis. Received: 14 April 1999     

The role of tumor necrosis factor (TNF)-α in the antitumor effect of intrapleural injection of Lactobacillus casei strain Shirota in mice

The involvement of several cytokines in the antitumor effect induced by intrapleural (i.pl.) injection of heat-killed cells of Lactobacillus casei strain Shirota (LC 9018) in mice was investigated. Injection of LC 9018 i.pl. into Meth A fibrosarcoma (Meth A)-bearing mice not only significantly prolonged the survival of the mice, but also effectively inhibited the accumulation of malignant pleural fluid in the thoracic cavity. In the thoracic cavity of tumor-bearing mice treated with LC 9018, we observed large amounts of several cytokines including interleukin (IL)-1β, interferon (IFN)-γ, IL-12 and tumor necrosis factor (TNF)-α. Both anti-IFN-γ and anti-IL-12 monoclonal antibody (mAb) treatments partially diminished the antitumor activity of LC 9018 in vivo, while the treatment of anti-IL-1β mAb did not influence the survival of the mice. However, anti-TNF-α mAb treatment completely abolished the antitumor effect of LC 9018 in vivo, suggesting that in this model LC 9018 has a survival-prolonging effect involving certain cytokines. Moreover, i.pl. injection of mouse recombinant TNF-α into Meth A-bearing mice pretreated with anti-TNF-α mAb partially restored the survival-enhancing effect of LC 9018. These results led us to conclude that TNF-α induced by i.pl. injection of LC 9018 plays an important role in the antitumor effect of LC 9018 in vivo. Received: 22 February 1999     

Effect of Heat-Killed Lactobacillus casei DKGF7 on a Rat Model of Irritable Bowel Syndrome

Non-viable bacteria, referred to as “paraprobiotics,” have attracted attention as potentially safer alternatives to probiotics. The aim of this study was to investigate the efficacy of heat-killed Lactobacillus casei DKGF7 on the symptomatic improvement of irritable bowel syndrome (IBS) in a rat disease model and to elucidate the underlying mechanisms that contribute to the beneficial effects of heat-killed probiotics. Seven male Wistar rats were induced with IBS by restraint stress and administered heat-killed L. casei DKGF7 for four weeks and then compared with seven rats in the control group. Stool consistency measured four weeks after initial treatment was the primary outcome measure. To investigate the mechanism of action of the heat-killed bacteria on IBS, we measured serum corticosterone levels, inflammatory cytokines in colon tissue, and expression of tight junction proteins (TJPs) in the epithelium. The treatment group showed significantly better stool consistency scores than the control group at week 4, as well as at every measured time point (all p values < 0.05). The treatment group showed lower serum corticosterone levels, lower colonic inflammatory cytokine levels, and higher expression of TJPs compared with the control group. Paraprobiotics such as heat-killed L. casei DKGF7 can improve stool consistency in a rat IBS model, which may indicate a potential therapeutic strategy for IBS treatment.     

Anti-alpha-Gal antibody titres remain unaffected by the consumption of fermented milk containing Lactobacillus casei in healthy adults

Alpha-Gal is a glycoconjugate present on cell membranes of non-primate mammals and bacteria, but not in humans, who display anti-Gal antibodies (ABs) in high titres. Probiotics contain bacterial strains which colonize the intestinal tract. In the present study, we investigated whether intake of fermented milk containing Lactobacillus casei (FML) affects anti-Gal AB titres. Serum was drawn from healthy probands (n = 19) for 6 weeks. After the second week, the probands consumed 125 ml of FML per day. Anti-Gal ABs of all isotypes and cytokines were measured. Bacterial cultures were bred from FML and bacteria were stained for alpha-Gal. Concentration of bacteria in FML was manifold higher than in conventional yoghurt (2 × 10⁵/g yoghurt vs. 1.1 × 10⁷/g FML). Both stained highly positive for Alpha-Gal. Alpha-Gal-specific ABs and cytokines remained unaffected by FML intake. Our results indicated that the consumption of FML does not elicit a humoral immune response in healthy adults.     

Antidiabetic effect of Lactobacillus casei CCFM0412 on mice with type 2 diabetes induced by a high-fat diet and streptozotocin

ObjectiveThe aim of this study was to evaluate the antidiabetic effects of Lactobacillus casei CCFM0412 on mice with type 2 diabetes induced by a high-fat diet and streptozotocin.MethodsThirty-two male C57 BL/6 J mice were assigned to four groups in this study. Type 2 diabetes was induced by feeding of a high-fat diet and injection of streptozotocin. L. casei CCFM0412 was administered to mice at a dose of 10⁹ cfu/d per mouse for 12 wk. Body weight, fasting and postprandial 2-h blood glucose, oral glucose tolerance, glycosylated hemoglobin, insulin, and glycogen in liver were measured. Endotoxin, tumor necrosis factor-α, and interleukin-10 levels were determined. Lipid metabolic parameters including triglycerides, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were also measured. The activities of glutathione peroxides, reactive oxygen species, and superoxide dismutase, and the levels of glutathione and malondialdehyde in the liver also were determined. Pancreas injury was evaluated by histologic analysis.ResultsAt 13 wk, L. casei CCFM0412 significantly decreased fasting and postprandial 2-h blood glucose, glycosylated hemoglobin, endotoxin, tumor necrosis factor-α, triglycerides, total cholesterol, low-density lipoprotein cholesterol, reactive oxygen species, and malondialdehyde levels compared with the control group (P < 0.05). The values for insulin, interleukin-10, high-density lipoprotein cholesterol, glutathione peroxides, superoxide dismutase, glutathione, and glycogen were significantly increased at 13 wk (P < 0.05). Islets of Langerhans in the L. casei CCFM0412 group were substantially protected from destruction compared with those in the control group.ConclusionL. casei CCFM0412 significantly improved glucose intolerance, dyslipidemia, immune-regulatory properties, and oxidative stress in mice with type 2 diabetes induced by a high-fat diet and streptozotocin. The results provide a sound rationale for future clinical trials of oral administration of L. casei CCFM0412 for the primary prevention of type 2 diabetes.     

Administration of yoghurt or lactobacillus casei to malnourished mice: Comparative effect on lymphoid cells and mucosal reconditioning of the intestine

The comparative effect of the administration of viable Lactobacillus casei and yoghurt on mucosal immunity, body weight and the recovery of intestinal microvilli was studied in malnourished mice. L. casei and yoghurt induced an increase in the number of cells producing IgA and IgM, yoghurt being more effective than L. casei. In both treatments, the number of CD4⁺ or CD8⁺ T‐lymphocytes did not reach the levels found in well‐nourished mice. However, yoghurt administration induced a slight increase in the number of CD8⁺cells and a significant increase in CD4⁺ helper T‐cells, compared with the malnourished control. Yoghurt was more effective than L. casei in improving the condition of intestinal microvilli and in the stimulation of mucus production. Yoghurt administration also induced an increase in body weight and avoided bacterial translocation of the normal intestinal microflora.     

Lactobacillus casei prevents impaired barrier function in intestinal epithelial cells

The exact effect of probiotics on epithelial barrier function is not well understood. The aims of this study were to evaluate cytokine-induced epithelial barrier dysfunction in intestinal epithelial cells (IECs) and to study the role of probiotics in the prevention of epithelial barrier dysfunction. Caco-2 cells grown on transwell chambers were stimulated with tumor necrosis factor (TNF)-α or interferon (IFN)-γ basolaterally. Probiotic, Lactobacillus casei, was added 1 h before cytokine stimulation. MAPK inhibitors were added 15 min before L. casei stimulation. The electrical resistance and paracellular permeability of Caco-2 monolayers were measured. Distribution of zonula occludens (ZO)-1 protein was assessed by immunofluorescence, and Western blot analyses for ZO-1, p-Akt, and toll-like receptor (TLR) 2 were performed. Both TNF-α and IFN-γ stimulation on Caco-2 cells decreased transepithelial resistance (TER), increased epithelial permeability, and decreased ZO-1 expression of Caco-2 cells. In contrast, pretreatment of L. casei reversed the cytokine-induced dysfunction of TER, epithelial permeability, and ZO-1 expression. Reversal of cytokine-induced dysfunction of TER and intestinal permeability by L. casei was abrogated with MAPK inhibitor treatment. Lactobacillus casei stimulation on Caco-2 cells increased TLR2 and p-Akt expression. Probiotic, L. casei, prevents cytokine-induced epithelial barrier dysfunctions in IECs.     

乳酸杆菌对ApoE~(-/-)小鼠动脉粥样斑块形成抑制作用

目的 研究乳酸杆菌对载脂蛋白E(apoE)基因缺陷小鼠动脉粥样斑块形成的影响,探讨乳酸杆菌抗动脉粥样硬化作用机制.方法 将apoE基因缺陷(ApoE~(-/-))小鼠随机分为4组:对照组(A组)、乳酸杆菌10~8组(B组)、乳酸杆菌10~(10)组(C组)、乳酸杆菌10~(12)(D组).A组喂养正常小鼠饲料(AIN-93),B、C、D组在正常饲料基础上添加10~8,10~(10),10~(12) cfu/mL乳酸杆菌喂养16周,检测动脉粥样斑块面积.结果 乳酸杆菌10~(12),10~(10),10~8 cfu/mL组的主动脉窦动脉粥样斑块面积分别为13.98%,17.36%,21.54%,比对照组的30.51%分别低54.18%,43.10%,29.40%,差异有统计学意义(P<0.05);随着乳酸杆菌浓度增加,主动脉窦动脉粥样斑块面积减少,但乳酸杆菌各组之间动脉粥样斑块面积差异无统计学意义.结论 乳酸杆菌可以抑制ApoE~(-/-)小鼠动脉粥样斑块形成,具有抗动脉粥样硬化作用.