Effects of fermented soymilk with Lacticaseibacillus paracasei YIT 9029 on gut microbiota and defecation habits: a randomised, double-blind, placebo-controlled study.

Previous studies have demonstrated that soymilk and Lacticaseibacillus paracasei YIT 9029 (strain Shirota: LcS) each beneficially affect the gut microbiota and defecation habits. To investigate the effects of daily consumption of fermented soymilk containing LcS (FSM), we conducted a randomised, double-blind, placebo-controlled study of 112 healthy Japanese adults with a low faecal Bifidobacterium count. They consumed 100 ml FSM or placebo (unfermented soymilk base) once daily for 4 weeks. Their gut microbiota was analysed by 16S rRNA gene amplicon sequencing and quantitative reverse transcription-polymerase chain reaction (PCR), and faecal short-chain fatty acids (SCFAs) and urinary putrefactive products were assessed during the pre- and post-consumption periods. Defecation habits were examined weekly using a subjective questionnaire. In the post-consumption period, living LcS were not detected in two subjects in the FSM group (n = 57) but were detected in one subject in the SM group (n = 55). The FSM group had a significantly higher number and relative abundance of faecal lactobacilli compared with the placebo group. The relative abundance of Bifidobacterium, alpha-diversity of microbiota, and concentrations of acetate and total SCFAs in faeces were significantly increased in the FSM group, although no significant differences were detected between the groups. The number of defecations and defecation days per week significantly increased in both groups. Subgroup analysis of 109 subjects, excluding 3 with inconsistent LcS detection (2 and 1 subjects in the FSM and SM groups, respectively), revealed that the FSM group (n = 55) had significantly greater increases in faecal acetate concentration compared with the SM group (n = 54) and significant upregulation of pathways related to energy production or glucose metabolism in the gut microbiota. These findings suggest that daily FSM consumption improves the gut microbiota and intestinal environment in healthy adults and may help to maintain health and prevent diseases. Registered at the University Hospital Medical Information Network (UMIN) clinical trials registry under: UMIN 000035612.

Effects of fermented soymilk with Lactobacillus casei Shirota on skin condition and the gut microbiota: a randomised clinical pilot trial.

Several clinical studies have shown that isoflavones and Lactobacillus casei Shirota (LcS) have beneficial effects on skin condition and the gut microbiota, respectively. Thus, we investigated the effects of consecutive intake of fermented soymilk (FSM) with LcS on skin condition and the gut microbiota, as well as isoflavone bioavailability, in a randomised, double-blind, placebo-controlled trial as a pilot study. Sixty healthy premenopausal Japanese women received FSM containing a moderate level of isoflavone aglycones and a probiotic LcS, or soymilk (SM) containing neither of them, twice a day for 8 weeks. Skin condition was assessed by a subjective questionnaire for face and morphological analysis of the stratum corneum on the inner forearm. Faecal microbiota and urinary isoflavone were analysed by 16S rRNA gene amplicon sequencing and high-performance liquid chromatography tandem mass spectrometry, respectively. Both the FSM and SM groups had improved skin condition as assessed from scores of overall satisfaction, dryness, moisture, elasticity, coarseness, pigmentation and/or stratum corneum morphology, as well as significantly increased levels of urinary isoflavones during the intake period compared with the pre-intake period, although there were no significant differences between the two groups. There was a significant positive correlation between urinary isoflavone levels and skin questionnaire scores. In contrast, the relative abundance levels of Lactobacillaceae significantly increased and those of Bifidobacteriaceae tended to increase during the intake period compared with the pre-intake period. For the after-intake period they only decreased significantly in the FSM group. The levels of Enterobacteriaceae and Porphyromonadaceae significantly decreased during the intake period in the FSM group. These findings suggest that daily intake of FSM, as well as SM, provides health benefits that improve skin condition via increased levels of isoflavone absorption in the body, and that only FSM beneficially modifies the gut microbiota in premenopausal healthy women.

Total skin electron beam therapy using an inclinable couch on motorized table and a compensating filter.

Total skin electron beam is a specialized technique that involves irradiating the entire skin from the skin surface to only a few millimetres in depth. In the Stanford technique, the patient is in a standing position and six different directional positions are used during treatment. Our technique uses large electron beams in six directions with an inclinable couch on motorized table and a compensating filter was also used to spread the electron beam and move its intensity peak. Dose uniformity measurements were performed using Gafchromic films which indicated that the surface dose was 2.04 ± 0.05 Gy. This technique can ensure the dose reproducibility because the patient is fixed in place using an inclinable couch on a motorized table.

Biological effects of probiotics: what impact does Lactobacillus casei shirota have on us?

Probiotics have been defined as live bacteria beneficial to the host when administered in adequate amounts. To evaluate the effect of probiotics on the prevention of carcinogenesis, Lactobacillus casei Shirota (LcS) was given to the patients who had undergone the resection of superficial bladder cancer, and administration of LcS significantly reduced the recurrence rate of bladder cancer. When LcS was given to the patients whose colonic polyps were surgically removed, the recurrence of colorectal cancer with moderate or severe atypia was suppressed. To assess the putative actions of LcS on innate immune responses, we examined the effect of LcS on natural killer (NK) cell activity in humans. Daily ingestion of fermented milk containing LcS restored NK cell activity in healthy subjects with low NK cell activity as well as human T lymphotropic virus (HTLV)-1-associated myelopathy patients. When peripheral blood mononuclear cells from healthy humans were cultured in the presence of heat-killed LcS, NK cell activity was augmented, which were partly mediated by monocyte-derived interleukin (IL)-12. These findings suggest that LcS may help the reinforcement of our defense system against cancer by modulating innate immune functions.

Interleukin-12 is involved in the enhancement of human natural killer cell activity by Lactobacillus casei Shirota.

We conducted a placebo-controlled, cross-over trial to examine the effect of Lactobacillus casei Shirota (LcS) on natural killer (NK) cell activity in humans. NK cell activity exhibited a declining trend during the period of placebo ingestion, but NK cell activity increased after intake for 3 weeks of fermented milk containing 4 x 10(10) live LcS. When human peripheral blood mononuclear cells were cultured in the presence of heat-killed LcS, NK cell activity was enhanced. The ability of LcS to enhance NK cell activity and induce interleukin (IL)-12 production was correlated, and the addition of anti-IL-12 monoclonal antibody reduced the enhancement of NK cell activity triggered by LcS. In addition, separation of NK cells from LcS-stimulated monocytes with membrane filter reduced NK cell activity to the intermediate level and almost deprived monocytes of the ability to produce IL-12. These results demonstrate that LcS can enhance NK cell activity in vivo and in vitro in humans, and IL-12 may be responsible for enhancement of NK cell activity triggered by LcS.

Induction of interleukin-12 by Lactobacillus strains having a rigid cell wall resistant to intracellular digestion.

Some strains of lactobacilli can stimulate macrophages and dendritic cells to secrete IL-12, which plays a key role in activating innate immunity. We examined the IL-12-inducing ability of 47 Lactobacillus strains belonging to 10 species in mouse peritoneal macrophages, and characterized the properties important for the induction of IL-12. Although considerable differences in IL-12-inducing ability were observed among the strains tested, almost all strains belonging to the Lactobacillus casei group (L. casei, Lactobacillus rhamnosus, and Lactobacillus zeae) or to Lactobacillus fermentum induced high levels of IL-12. Phagocytosis of lactobacilli was necessary for IL-12 induction, and the strains with strong IL-12 induction were relatively resistant to lysis in the macrophages. The sensitivity of Lactobacillus strains to in vitro treatment with M-1 enzyme, a member of the N-acetylmuramidases, was negatively correlated with IL-12-inducing ability. Using a probiotic strain, L. casei strain Shirota (LcS), we showed that the cell wall of LcS could be digested by long-term treatment with a high dose of M-1 enzyme and that the IL-12-inducing ability was diminished according to the duration of the enzyme treatment. The soluble polysaccharide-peptidoglycan complex released from the cell wall of LcS did not induce IL-12, whereas the insoluble intact cell wall of LcS induced IL-12. These results suggest that the intact cell wall structure of lactobacilli is an important element in the ability to induce IL-12 and that Lactobacillus strains having a rigid cell wall resistant to intracellular digestion effectively stimulate macrophages to induce IL-12.

The cell death machinery controlled by Bax and Bcl-XL is evolutionarily conserved in Ciona intestinalis.

Bax and Bcl-XL are key regulators of apoptosis in mammals. Here we report the functional characterization of two Bcl-2 homologues, ciBax and ciBcl-XL, in a basal invertebrate-chordate ascidian Ciona intestinalis. CiBax is a Ciona homologue of the BH1-3 pro-apoptotic protein Bax, whereas ciBcl-XL is a Bcl-XL-like anti-apoptotic protein. Molecular modeling analysis showed that ciBax and ciBcl-XL share both sequence and structural similarities to human Bax and Bcl-XL, respectively. Like their human counterparts, ciBax could form a homodimer or oligomers as well as heterodimerize with ciBcl-XL, and overexpression of ciBax caused apoptosis that could be attenuated by ciBcl-XL. Mutagenesis studies showed that the BH3 domain of ciBax is critical for its cell death-inducing function and also for its interaction with ciBcl-XL. In Ciona embryos, ectopic expression of ciBax but not its BH3 deletion mutant resulted in cell dissociation and apoptosis after late gastrula stage of embryonic development. Moreover, not only wild type ciBcl-XL but also a mutant ciBcl-XL(F101V), which is unable to interact with ciBax, could block cell dissociation and developmental deficit in Ciona embryos induced by overexpression of ciBax. Taken together, these findings suggest that functional homologues of both the BH1-3 death effector Bax and the pro-survival Bcl-XL exist in sea squirt Ciona intestinalis, and they control the cell death machinery independent of their heterodimerization.

Lactobacillus casei strain Shirota suppresses serum immunoglobulin E and immunoglobulin G1 responses and systemic anaphylaxis in a food allergy model.

BACKGROUND: Our previous study using allergen-sensitized murine splenocyte cultures has shown that Lactobacillus casei strain Shirota (LcS), a lactic acid bacterium widely used as a starter for fermented milk products, suppresses IgE production through promoting a dominant Th1-type response mediated by IL-12 induction. OBJECTIVE: We tried to evaluate the ability of LcS to suppress both IgE response and allergic reactions in vivo using a food allergy model with ovalbumin-specific T cell receptor transgenic (OVA-TCR-Tg) mice. METHODS: The ability of heat-killed LcS to induce IL-12 in serum was tested. OVA-TCR-Tg mice were fed a diet containing OVA for 4 weeks and injected with LcS intraperitoneally three times in the first week of this period. Cytokine and antibody secretion by splenocytes, and serum IgE and IgG1 responses were examined. The inhibitory effect of LcS on systemic anaphylaxis induced by intravenous challenge of OVA-fed OVA-TCR-Tg mice with OVA was also tested. RESULTS: Intraperitoneal injection of LcS induced an IL-12 response in the serum of OVA-TCR-Tg mice. In the food allergy model, LcS administration skewed the pattern of cytokine production by splenocytes toward Th1 dominance, and suppressed IgE and IgG1 secretion by splenocytes. The ability of LcS to modulate cytokine production was blocked by anti-IL-12 antibody treatment. LcS also inhibited serum OVA-specific IgE and IgG1 responses and diminished systemic anaphylaxis. CONCLUSION: LcS administration suppresses IgE and IgG1 responses and systemic allergic reactions in a food allergy model, suggesting a possible use of this lactic acid bacterium in preventing food allergy.

Three soluble form messages of murine CD46 are produced through alternative mRNA splicing.

Murine CD46 (mCD46) is a type 1 membrane protein expressed predominantly in testicular germ cells, the distribution profile of which is in contrast to that of human CD46 showing a ubiquitous tissue distribution. We have identified an additional message of mCD46 that encodes a putative secretory form [Nomura et al. (1999) Immunogenetics 50, 245-254]. Here, we cloned three cDNAs encoding putative soluble CD46 from murine testis. These soluble form messages were yielded on insertion of unidentified nucleotide sequences, 77, 179, and 73 ntds, into the junctions between the SCR3 and SCR4 (variant 2), ST(c) and UK (variant 3), and SCR4 and ST(c) (variant 1) domains, respectively, the last one corresponding to the reported soluble form. The exons corresponding to these three inserts were identified in the murine CD46 genome, indicating that the alternative splicing of mRNA participates in the generation of these various CD46 messages. In normal mouse sera and cell lines, however, virtually no soluble CD46 was detected on immunoblotting. On Northern blotting analysis with specific probes, on the other hand, variant 1 was found to be predominantly expressed in the liver and heart. In addition, all variant messages were detected on PCR in all organs examined. When a rabbit cell line, RK13 cells, was transfected with cDNA of variant 1, protein synthesis was detected on immunoblotting. Although the mCD46 protein production was inefficient, this variant 1 exhibited factor I-cofactor activity as to inhibition of the complement cascade. Since the mCD46 protein was reported to be markedly up-regulated on infection of murine cells with mCMV, the soluble mCD46 proteins may act as a complement regulator that controls the systemic complement system under the conditions of a viral infection.

High serum levels of additional IL-18 forms may be reciprocally correlated with IgE levels in patients with atopic dermatitis.

We established an ELISA system for determination of as yet unidentified species of interleukin 18 (IL-18), named IL-18 type 2, in human serum. Serum IL-18 levels and their effect on IgE levels were examined in 18 patients with atopic dermatitis (AD) with no other allergic symptoms. Three of these patients showed high IL-18 type 2 concentrations (25-100 ng/ml) in their blood serum, and this IL-18 type 2 was detectable only with our established ELISA system. In contrast, the level of the conventional form of IL-18 (type 1) was found to be 50-400 pg/ml in all patients by the commercially available ELISA. The levels of type 1 IL-18 showed no correlation with those of type 2 and approximately 2-fold higher in AD patients than in normal subjects. IL-12 p40 and IgE levels were correlated in the patients with no IL-18 type 2, and interestingly, relatively low IgE concentrations were detected in the three IL-18 type 2-positive patients. They showed considerable levels of IL-12 p40 unlike normal subjects. The IFNgamma-inducing activity of IL-18 type 2 was >100-fold less potent by weight ratio than that of a recombinant 'active' IL-18 preparation, even after the treatment with Caspase 1. Although the relationship between AD and serum IgE levels is not clear cut, IL-18 type 2 appears to play some roles in the Th2-polarization involving IgE production in association with immune responses occurring in local inflammatory milieu such as atopic lesions.

Distribution of IL-18 and IL-18 receptor in human skin: various forms of IL-18 are produced in keratinocytes.

Human interleukin-18 (IL-18) enhances IL-12-mediated IFN-gamma production by lymphocytes and Fas/perforin-mediated cytolysis by NK cells. IL-18 is synthesized as a 24 kDa proform, and the proform is processed in the cytoplasm into an 18 kDa mature form. Active and precursor forms of IL-18 have been detected in immunocompetent cells, and active IL-18 exerts its functions through its receptor. We sought to determine which human skin cells are responsible for production of IL-18 and which express its receptor. Monoclonal antibodies against human IL-18 and polyclonal antibody against IL-18 receptor were provided for this analysis. Formalin-embedded and frozen sections of human epidermis were analyzed by immunoperoxidase and immunofluorescence staining. IL-18 was detected in all living cell layers of the epidermis, hair follicles, arrectores pilorum, eccrine ducts and endothelial cells. IL-18 was localized in the cytoplasm of cells in living epidermal cell layers. In contrast, IL-18 receptor was mainly detected in keratinocytes and expressed in the cell periphery in living cell layers. Since keratinocytes were the main source of IL-18 and its receptor, cultured human keratinocytes were further analyzed by immunoblotting. IL-18 receptor was identified as an 80 kDa single band. The mature 18 kDa and precursor 24 kDa forms of IL-18 were detected by our monoclonal antibody (mAb) 21 and mAb 132, respectively, while only the 18 kDa form was detected by a commercial mAb, 125-2H. Cultured keratinocytes showed positive granular staining for IL-18 in the cytoplasm and positive staining for IL-18 receptor mainly in the cell periphery. Our findings indicate that mature IL-18, precursor IL-18 and IL-18 receptor are simultaneously expressed with different localizations by human epidermal keratinocytes. Keratinocytes might be activated by their own IL-18 in an autocrine or paracrine fashion.

Interferon gamma-producing ability in blood lymphocytes of patients with lung cancer through activation of the innate immune system by BCG cell wall skeleton.

An in vitro assay system was developed to assess the potency of the human innate immune system by measurement of IL-12, IL-18, IL-10 and IFNgamma in the supernatants of bacillus Calmette-Guerin cell wall skeleton (BCG-CWS)-stimulated blood samples. BCG-CWS is a ligand for Toll-like receptor (TLR) 2 and 4, and activates monocytes to macrophages (Mphi), and immature dendritic cells to mature antigen-presenting cells (APC). This system was found to allow the discrimination of immune suppressive states in patients with lung cancer from normal immune states in light of the cytokine profile. The following results were deduced from analyses of BCG-CWS-stimulated blood samples of lung cancer patients with reference to normal subjects. (1) The levels of production of IFNgamma and IL-10 by lymphocytes were decreased. (2) IL-12 p40 production by monocytes/Mphi was upregulated, while that of IL-10 was downregulated. (3) IL-18 was detected in all patients in a range similar to normal subjects. (4) Responses of lymphocytes to IL-2 and IL- 18 in terms of IFNgamma production were diminished. (5) The upregulated IL-12 levels were recovered to within the normal range in most patients after tumor resection. (6) Male patients showed more severe suppression of IL-12/IL-18-mediated IFNgamma production than female patients. Thus, the lesser IFNgamma production observed in patients' blood with high IL-12 p40 levels in response to BCG-CWS may reflect the production of p40 dimers or IL-23 instead of p70, or the presence of some unknown pathways to prohibit the interface between the innate and acquired immune systems. BCG-CWS-mediated Toll signaling may participate in IFNgamma induction for lymphocytes through Mphi/APC IL-12/I-18 modulation.

An alternative form of IL-18 in human blood plasma: complex formation with IgM defined by monoclonal antibodies.

Monoclonal Abs 21 and 132 were raised against human functionally inactive rIL-18, and plasma IL-18 levels were determined by the sandwich ELISA established with these mABS: Plasma IL-18, designated type 2, was detected by this ELISA, and the levels found were not consistent with those obtained with the commercially available kit for determination of functionally active IL-18 (type 1). Type 1 was detected in all volunteers, whereas type 2 was detected in approximately 30% of healthy subjects, and the levels of type 2 in their blood plasma were high (25-100 ng/ml) compared with those of type 1 (0.05-0.3 ng/ml). We purified IL-18 type 2 from blood plasma of volunteers with high IL-18 type 2 concentrations, and its M(r) was determined to be 800 kDa by SDS-PAGE and molecular sieve HPLC. The purified 800-kDa protein, either caspase-1-treated or untreated, expressed no or marginal IL-18 function in terms of potentiation of NK-mediated cytolysis and IFN-gamma induction, and it barely bound IL-18R-positive cells. N-terminal amino acid analysis indicated that the purified protein was IgM containing a minimal amount of IL-18 proform and its fragment. Again, the purified IgM from IL-18 type2-positive volunteers exhibited cross-reaction with mAb 21 against IL-18. This band was not detected with 125-2H, an mAb against functionally active IL-18. Hence, human IgM carries functionally inactive IL-18 forming a disulfide-bridged complex, and this IL-18 moiety is from 10- to 100-fold higher than the conventional type 1 IL-18 in blood circulation in approximately 30% normal subjects.

Effect of intranasal administration of Lactobacillus casei Shirota on influenza virus infection of upper respiratory tract in mice.

In mice administered Lactobacillus casei strain Shirota (LcS) intranasally, potent induction of interleukin 12, gamma interferon, and tumor necrosis factor alpha, which play a very important role in excluding influenza virus (IFV), was evident in mediastinal lymph node cells. In this model of upper respiratory IFV infection, the titers of virus in the nasal wash of mice inoculated with 200 microg of LcS for three consecutive days (LcS 200 group) before infection were significantly (P < 0.01) lower than those of mice not inoculated with LcS (control group) (10(0.9 +/- 0.6) versus 10(2.1 +/- 1.0)). The IFV titer was decreased to about 1/10 of the control level. Using this infection model with modifications, we investigated whether the survival rate of mice was increased by intranasal administration of LcS. The survival rate of the mice in the LcS 200 group was significantly (P < 0.05) greater than that of the mice in the control group (69% versus 15%). It seems that the decrease in the titer of virus in the upper respiratory tract to 1/10 of the control level was important in preventing death. These findings suggest that intranasal administration of LcS enhances cellular immunity in the respiratory tract and protects against influenza virus infection.

Human macrophages produce dimeric forms of IL-18 which can be detected with monoclonal antibodies specific for inactive IL-18.

We established two monoclonal antibodies (mAbs) which specifically recognize human 'functionally inactive' recombinant IL-18, and IL-18 protein polymorphism was examined using human monocytes and macrophages (M phi). In 6 day GM-CSF-treated M phi, an 'inactive' IL-18-recognizing mAb 21 detected the IL-18 proform (24 kDa) and a 48-kDa protein, which were gradually increased concomitant with maturation stage. Majority of the 24- and 48-kDa forms were barely detectable with other mAbs recognizing 'active' IL-18. No reagents including Toll stimulators up-regulated these IL-18 populations in M phi. The 21-recognizable IL-18 species were separated using an anion-exchanger column and their IFN gamma-inducing activity was assessed with human lymphocytes plus IL-12. Virtually no as yet known activity was detected with these IL-18 species. After processed with M phi proteases, an 18-kDa form was generated to express the IFN gamma-inducing activity, although the activity was far weaker than that of control 'active' IL-18. These observations suggested that large amounts of various IL-18 species are produced with monocyte-M phi differentiation and most of these IL-18 species are functionally 'inactive' in terms of the reported IL-18 function even after proteolytic 18-kDa conversion.

Serum IgE response to orally ingested antigen: a novel IgE response model with allergen-specific T-cell receptor transgenic mice.

BACKGROUND: The mechanism by which orally ingested allergens elicit an IgE response remains unclear because there are few animal models available for investigation of this response. OBJECTIVE: We tried to develop a murine model suitable for investigation of the IgE response to orally ingested allergens, which would allow us to identify T cells that could promote IgE production. METHODS: Ovalbumin (OVA)-specific T-cell receptor transgenic mice were fed a diet containing OVA, and both the serum antibody response and cytokine production by splenocytes were examined. RESULTS: Oral administration of OVA to transgenic mice led to an increase in the levels of both antigen-specific IgE and total IgE in the sera. Subsequent intravenous challenge of OVA-fed transgenic mice with OVA resulted in anaphylactic shock. Analysis of cytokine production by splenocytes revealed that high IL-4-producing T cells appeared in the spleen 1 week after the start of feeding the OVA diet. T cells from these mice were found to promote IgE secretion by BALB/c B cells in vitro. This helper activity and the levels of IL-4 secretion were diminished after long-term feeding. These findings suggest the possibility that the orally ingested antigen elicited a response by a subpopulation of T cells that produce high levels of T(H2)-type cytokines and that promote IgE secretion, and these same T cells were tolerized by the orally ingested antigen. CONCLUSION: This experimental model with transgenic mice may be a useful tool for further studies of the cellular and molecular mechanisms of the T-cell and IgE responses to orally ingested antigens.

A comparative analysis of the antigenic, structural, and functional properties of three different preparations of recombinant human interleukin-18.

We compared the structural and functional properties of three recombinant human interleukin-18 (rIL-18) preparations, commercially available (Pep rIL-18) and prepared in our laboratory (active and inactive, according to their ability to potentiate IL-12-mediated interferon-gamma [IFN-gamma] induction in lymphocytes). All three preparations showed multimer formation on SDS-PAGE/immunoblotting using monoclonal antibodies (mAb) against the inactive form of rIL-18. In contrast, only the 18-kDa bands were recognized in each sample by mAb against the active form of rIL-18. The amounts of multimers and the 18-kDa moiety of Pep rIL-18 resembled those of the inactive rather than the active form. Likewise, the reaction profile of Pep rIL-18 toward mAb was very similar to that of inactive but not active rIL-18 on sandwich ELISA. Pep rIL-18 potentiated IFN-gamma-inducing activity together with IL-12, but its potency was 100-fold less than that of the active rIL-18, and excess doses were required for its activity. The inactive rIL-18 showed virtually no IFN-gamma-inducing ability, but when reduced and reconstituted, it inhibited the IFN-gamma-inducing activity of active rIL-18. These results suggest that there are two categories of recombinant IL-18 that are structurally, functionally, and antigenically different, and the mAb 125-2H and 21 can discriminate these two IL-18 populations by recognizing the epitopes specifically expressed on active and inactive IL-18, respectively.

The 3'-UT of the ubiquitous mRNA of human CD46 confers selective suppression of protein production in murine cells.

Mice express CD46 protein and its approximately 1.5-kb mRNA only in the testicular germ cells, unlike primates and pigs which ubiquitously express CD46 and its approximately 4 kb mRNA. Human CD46 is not well expressed in transgenic mice carrying human CD46 cDNA. To analyze the mechanism of regulation of human CD46 expression in mouse cells, we cloned the long (ubiquitous approximately 4 kb, L-form) and short ( approximately 1.5 kb, S-form) forms of human CD46 cDNA whose size difference is due to a stretch of the 3'-UT. Transfection of either cDNA resulted in marked S-form-dependent protein generation in all mouse cell lines tested. In contrast, there were virtually no differences in protein synthesis between S- and L-form cDNA in the simian and swine cell lines. Quantitative mRNA analyses and luciferase reporter gene assays suggested that one major cause of this interspecies discrepancy is transcriptional regulation, i. e. selective suppression of the 4-kb mRNA leading to low levels of protein synthesis. Although other mechanisms such as mRNA stability and translational regulation may lead to the low expression levels of L-form-derived CD46 in mice, the silencer activity in the L-form 3'-UT appears to function in human CD46 transcriptional regulation in mice.

Immunomodulatory function of lactic acid bacteria.

Using mice, we found that oral administration of Bifidobacterium breve YIT4064 (B. breve) activated the humoral immune system, augmented anti-rotavirus IgA production or anti-influenza virus (IFV) IgG production and protected against rotavirus infection or influenza infection, respectively. Furthermore, when the B. breve was given to infants from an infant home, there was a significant reduction of the frequency of rotavirus shedding in stool samples during the administration of the bacteria. It was also found, again using mice, that oral administration of Lactobacillus casei strain Shirota (LcS) stimulated type 1 helper T (Th1) cells, activated the cellular immune system and inhibited incidence of tumors and IgE production. These results demonstrated that these two strains of lactic acid bacteria modulated the different immune systems each in its own way and prevented against various diseases.