Honglin Dong

Selective effects of Lactobacillus casei Shirota on T cell activation, natural killer cell activity and cytokine production

Modulation of host immunity is an important potential mechanism by which probiotics confer health benefits. This study was designed to investigate the effects of a probiotic strain, Lactobacillus casei Shirota (LcS), on immune function using human peripheral blood mononuclear cells (PBMC) in vitro. In addition, the role of monocytes in LcS‐induced immunity was also explored. LcS promoted natural killer (NK) cell activity and preferentially induced expression of CD69 and CD25 on CD8+ and CD56+ subsets in the absence of any other stimulus. LcS also induced production of interleukin (IL)‐1β, IL‐6, tumour necrosis factor (TNF)‐α, IL‐12 and IL‐10 in the absence of lipopolysaccharide (LPS). In the presence of LPS, LcS enhanced IL‐1β production but inhibited LPS‐induced IL‐10 and IL‐6 production, and had no further effect on TNF‐α and IL‐12 production. Monocyte depletion reduced significantly the impact of LcS on lymphocyte activation, cytokine production and natural killer (NK) cell activity. In conclusion, LcS activated cytotoxic lymphocytes preferentially in both the innate and specific immune systems, which suggests that LcS could potentiate the destruction of infected cells in the body. LcS also induced both proinflammatory and anti‐inflammatory cytokine production in the absence of LPS, but in some cases inhibited LPS‐induced cytokine production. Monocytes play an important role in LcS‐induced immunological responses.

Ageing impairs the T cell response to dendritic cells

Dendritic cells (DCs) are critical in priming adaptive T-cell responses, but the effects of ageing on interactions between DCs and T cells are unclear. This study investigated the influence of ageing on the maturation of and cytokine production by human blood-enriched DCs, and the impact on T cell responses in an allogeneic mixed leucocyte reaction (MLR). DCs from old subjects (65-75 y) produced significantly less TNF-α and IFN-γ than young subjects (20-30 y) in response to lipopolysaccharide (LPS), but expression of maturation markers and co-stimulatory molecules was preserved. In the MLR, DCs from older subjects induced significantly restricted proliferation of young T cells, activation of CD8+ T cells and expression of IL-12 and IFN-γ in T cells compared with young DCs. T cells from older subjects responded more weakly to DC stimulation compared with young T cells, regardless of whether the DCs were derived from young or older subjects. In conclusion, the capacity of DCs to induce T cell activation is significantly impaired by ageing.

Effect of a synbiotic on the response to seasonal influenza vaccination is strongly influenced by degree of immunosenescence.

BackgroundAgeing increases risk of respiratory infections and impairs the response to influenza vaccination. Pre- and probiotics offer an opportunity to modulate anti-viral defenses and the response to vaccination via alteration of the gut microbiota. This study investigated the effect of a novel probiotic, Bifidobacterium longum bv. infantis CCUG 52,486, combined with a prebiotic, gluco-oligosaccharide (B. longum + Gl-OS), on the response to seasonal influenza vaccination in young and older subjects in a double-blind, randomized controlled trial, taking into account the influence of immunosenescence markers at baseline.ResultsVaccination resulted in a significant increase in total antibody titres, vaccine-specific IgA, IgM and IgG and seroprotection to all three subunits of the vaccine in both young and older subjects, and in general, the increases in young subjects were greater. There was little effect of the synbiotic, although it tended to reduce seroconversion to the Brisbane subunit of the vaccine and the vaccine-specific IgG response in older subjects. Immunological characterization revealed that older subjects randomized to the synbiotic had a significantly higher number of senescent (CD28−CD57+) helper T cells at baseline compared with those randomized to the placebo, and they also had significantly higher plasma levels of anti-CMV IgG and a greater tendency for CMV seropositivity. Moreover, higher numbers of CD28−CD57+ helper T cells were associated with failure to seroconvert to Brisbane, strongly suggesting that the subjects randomized to the synbiotic were already at a significant disadvantage in terms of likely ability to respond to the vaccine compared with those randomized to the placebo.ConclusionsAgeing was associated with marked impairment of the antibody response to influenza vaccination in older subjects and the synbiotic failed to reverse this impairment. However, the older subjects randomized to the synbiotic were at a significant disadvantage due to a greater degree of immunosenscence at baseline compared with those randomized to the placebo. Thus, baseline differences in immunosenescence between the randomized groups are likely to have influenced the outcome of the intervention, highlighting the need for detailed immunological characterization of subjects prior to interventions.Trial registrationClinicaltrials.gov NCT01066377.

Flavanone-rich citrus beverages counteract the transient decline in postprandial endothelial function in humans: a randomised, controlled, double-masked, cross-over intervention study

Specific flavonoid-rich foods/beverages are reported to exert positive effects on vascular function; however, data relating to effects in the postprandial state are limited. The present study investigated the postprandial, time-dependent (0-7 h) impact of citrus flavanone intake on vascular function. An acute, randomised, controlled, double-masked, cross-over intervention study was conducted by including middle-aged healthy men (30-65 years, n 28) to assess the impact of flavanone intake (orange juice: 128·9 mg; flavanone-rich orange juice: 272·1 mg; homogenised whole orange: 452·8 mg; isoenergetic control: 0 mg flavanones) on postprandial (double meal delivering a total of 81 g of fat) endothelial function. Endothelial function was assessed by flow-mediated dilatation (FMD) of the brachial artery at 0, 2, 5 and 7 h. Plasma levels of naringenin/hesperetin metabolites (sulphates and glucuronides) and nitric oxide species were also measured. All flavanone interventions were effective at attenuating transient impairments in FMD induced by the double meal (7 h post intake; P<0·05), but no dose-response effects were observed. The effects on FMD coincided with the peak of naringenin/hesperetin metabolites in circulation (7 h) and sustained levels of plasma nitrite. In summary, citrus flavanones are effective at counteracting the negative impact of a sequential double meal on human vascular function, potentially through the actions of flavanone metabolites on nitric oxide.

Impact of ageing and a synbiotic on the immune response to seasonal influenza vaccination: a randomised controlled trial

Summary Background & aims Ageing increases risk of respiratory infections and impairs the response to influenza vaccination. Pre- and pro-biotics offer an opportunity to modulate anti-viral defenses and the response to vaccination via alteration of the gut microbiota. This study investigated the effect of a novel probiotic, Bifidobacterium longum bv. infantis CCUG 52486, combined with a prebiotic, gluco-oligosaccharide, on the B and T cell response to seasonal influenza vaccination in young and older subjects . Methods In a double-blind, randomized controlled trial, 58 young (18–35 y) and 54 older (60–85 y) subjects were supplemented with the synbiotic for 8 weeks. At 4 weeks they were administered with a seasonal influenza vaccine. B and T cell phenotype and responsiveness to in vitro re-stimulation with the vaccine were assessed at baseline, 4, 6 and 8 weeks. Results B and T cell profiles differed markedly between young and older subjects. Vaccination increased numbers of memory, IgA+ memory, IgG+ memory and total IgG+ B cells in young subjects, but failed to do so in older subjects and did not significantly alter T cell subsets. Seroconversion to the H1N1 subunit in the older subjects was associated with higher post-vaccination numbers of plasma B cells, but seroconversion was less consistently associated with T cell phenotype. B and T cell subsets from both young and older subjects demonstrated a strong antigen-specific recall challenge, and although not influenced by age, responsiveness to the recall challenge was associated with seroconversion. In older subjects, CMV seropositivity was associated with a significantly lower recall response to the vaccine, but the synbiotic did not affect the responsiveness of B or T cells to re-stimulation with influenza vaccine. Conclusions Antigen-specific B and T cell activation following an in vitro recall challenge with the influenza vaccine was influenced by CMV seropositivity, but not by a synbiotic. Registered under ClinicalTrials.gov Identifier no. NCT01066377.

Addition of Orange Pomace to Orange Juice Attenuates the Increases in Peak Glucose and Insulin Concentrations after Sequential Meal Ingestion in Men with Elevated Cardiometabolic Risk

BACKGROUND Prospective cohort studies show that higher dietary fiber intake is associated with reduced cardiovascular disease risk, yet the impact on postprandial glucose and insulin responses is unclear. OBJECTIVE This study aims to evaluate the effects of orange beverages with differing fiber concentrations on postprandial glycemic responses (secondary outcome measure) after a sequential breakfast and lunch challenge in men with increased cardiometabolic risk. METHODS Thirty-six men (aged 30-65 y; body mass index 25-30 kg/m(2): fasting triacylglycerol or total cholesterol concentrations: 0.8-2.2 or 6.0-8.0 mmol/L, respectively) were provided with a high-fat mixed breakfast and were randomly assigned to consume 240 mL Tropicana (PepsiCo, Inc.) pure premium orange juice without pulp (OJ), OJ with 5.5 g added orange pomace fiber (OPF), juice made from lightly blended whole orange, or an isocaloric sugar-matched control (Control) on 4 occasions separated by 2 wk. A medium-fat mixed lunch was provided at 330 min. Blood samples were collected before breakfast and on 11 subsequent occasions for 420 min (3 time points postlunch) to determine postprandial glucose, insulin, lipid, and inflammatory biomarker responses. Repeated-measures ANOVA was used for data analysis. RESULTS OPF significantly (P < 0.05) reduced the maximal change in glucose concentrations (1.9 ± 0.21 mmol/L) reached after breakfast compared with other treatments (2.3-2.4 mmol/L) and after lunch (3.0 ± 0.05 mmol/L) compared with OJ (3.6 ± 0.05 mmol/L). The maximal change in insulin concentration (313 ± 25 pmol/L) was also lower compared with Control (387 ± 30 pmol/L) and OJ (418 ± 39 pmol/L) after breakfast. OPF significantly delayed the time to reach the peak glucose concentration compared with Control and OJ, and of insulin compared with Control after breakfast. CONCLUSION OPF consumed with breakfast may lower postprandial glycemic and insulinemic responses to typical meal ingestion in men with increased cardiometabolic risk. This trial is registered at clinicaltrials.gov as NCT01963416.

Age-related Changes in the Natural Killer Cell Response to Seasonal Influenza Vaccination are not Influenced by a Synbiotic; a Randomised Controlled Trial

Natural killer (NK) cells are an important component of the immune response to influenza infection, but are subject to alteration during aging, which may play a role in impaired response to infection and vaccination in older people. Enhancement of NK cell activity could, therefore, present a means to improve the immune response to vaccination in older subjects, and pre- and probiotics offer an opportunity to modulate antiviral defenses via alteration of the gut microbiota. This study investigated the effect of a novel probiotic, Bifidobacterium longum bv. infantis CCUG 52486, combined with a prebiotic, gluco-oligosaccharide (B. longum + Gl-OS), on the NK cell response to seasonal influenza vaccination in young and older subjects in a double-blind, randomized controlled trial. There were significant effects of aging on NK cell phenotype, the most notable of which were an increase in CD56dim cells, mainly reflected in the CD16+ subset, a decrease in CD56bright cells, mainly reflected in the CD16− subset, and greater expression of the immunosenescence marker, CD57, on NK cell subsets. However, these changes only partially translated to differences in NK cell activity, observed as trends toward reduced NK cell activity in older subjects when analyzed on a per cell basis. Influenza vaccination increased the proportion of CD56bright cells and decreased the proportion of CD56dim cells, in young, but not older subjects. Although NK cell activity in response to vaccination was not significantly different between the young and older subjects, low post-vaccination NK cell activity was associated with poor seroconversion in only the older subjects. There was no influence of the synbiotic on NK cell phenotype or activity, either before or after influenza vaccination. In conclusion, aging is associated with marked alteration of the phenotype of the NK cell population and there was evidence of an impaired NK cell response to influenza vaccination in older subjects. The effects of aging on NK cell phenotype and activity could not be offset by B. longum + Gl-OS. Clinical Trial Registration www.ClinicalTrials.gov, identifier NCT01066377.

Effects of Lactobacillus casei Shirota on immune function

Modulation of host immunity is an important potential mechanism by which probiotics confer health benefits. The present study was designed to investigate the effect of a probiotic strain Lactobacillus casei Shirota (LcS) on the immune function using human peripheral blood mononuclear cells (PBMC) in vitro. PBMC were obtained from eleven healthy adults. LcS were grown in MRS broth (CD0359; Oxoid Ltd, Basingstoke, Hants., UK) anaerobically and harvested in the exponential phase. PBMC (2 · 10 cells/ml) were exposed to three different concentrations of viable LcS for 24 h with or without 2.5mg concanavalin A (ConA)/ml. The activation markers, CD69 and CD25, on T-cell subsets were assessed by flow cytometry. Whole blood (WB) or PBMC were stimulated for 24 h by three different concentrations of viable LcS with or without 1mg lipopolysaccharide (LPS)/ml and cytokines were measured by ELISA. In the absence of ConA LcS induced expression of both CD69 and CD25 on CD8+ T-cell subset, but had less effect on CD4 + T-cells and LcS had no further effect on ConA-stimulated cultures (Fig 1). The maximal effect was seen with 10 CFU/ml, representing an LcS:PBMC of 1:1. LcS alone induced production of IL-1b, IL-6, TNFa, IL-12 and IL-10, but greatly inhibited LPS-induced IL-10 and IL-6 production (Fig 2). Cytokine production was also measured in WB. Production of cytokines in response to LcS and/or LPS by PBMC and WB was highly correlated (r 0.69–0.83, P<0.01).

Bifidobacterium longum bv. infantis CCUG 52486 combined with gluco-oligosaccharide significantly reduces the duration of self-reported cold and flu-like symptoms among healthy older adults after seasonal influenza vaccination

The potential health benefits of both preand probiotics have expanded in recent years from maintaining bowel regularity and a balance of gut microflora to improving micronutrient status and immune function. There is particular interest in the positive influences of preand probiotics in older people, who are subject to alteration in gut microbiota composition and also to immunosenescence (deterioration and dysregulation of the immune system). The PRIMAGE study is a randomised, double-blind, placebo-controlled, parallel study investigating the influence of Bifidobacterium longum bv. Infantis CCUG 52486 (5 · 10 CFU/d) combined with gluco-oligosaccharide (8 g/d) on the immune response to influenza vaccination among healthy young (18–35 y, n = 58) and older (60–85 y, n = 54) volunteers. Volunteers consumed either a placebo (9 g/d maltodextrin) or treatment for a total of 8 weeks, and a trivalent influenza vaccination (2010/2011 northern hemisphere) was administered after 4 wks of treatment. Blood and faecal samples were collected at baseline, week 4 and after vaccination. Older volunteers were asked to complete a self-reported illness form for six months post-vaccination. 43 healthy older volunteers were vaccinated in October/November 2010 in accordance with UK NHS vaccination schedules, and 41 returned a six-month self-reported illness form. Treatment did not significantly alter the incidence of cold or flu-like symptoms. Three participants within the treatment group reported a sudden onset of flu like illness, resulting in a significantly higher duration of this symptom among volunteers on treatment in the six months post-vaccination (p = 0.0047). Volunteers receiving treatment had significantly lower cumulative duration of fatigue, runny nose, headache and sore throat symptoms during the six months post-vaccination compared to placebo (p<0.0001).

Effects of Bifidobacteriumlongum bv. Infantis CCUG 52486 combined with glucooligosaccharide on immune cell populations in healthy young and older subjects receiving an influenza vaccination

Probiotics have been suggested to modulate immune function in young and older subjects. However, the data is inconsistent, the mechanisms are not well characterised, and the influence of immunological ageing is unclear. The aim of the current study was to investigate the impact of a novel probiotic, with a suitable prebiotic, on the immune response to influenza vaccination in healthy young and older subject. In a randomised, double-blind, placebo-controlled trial, 54 older subjects (69 4.6 y) and 58 young subjects (26 4.2 y) consumed either 5 · 10 CFU of Bifidobacteriumlongumbv.infantisCCUG 52486 combined with 8 g of glucooligosaccharide (GIOS), or placebo (9 g maltodextrin) daily for 8 weeks in total. After 4 weeks, subjects received an influenza vaccine (2010/2011 season). Quantification of T cells, NK cells and B cells was performed by flowcytometryat baseline and 4, 6 and 8 weeks after supplementation. Statistical analysis was performed using SPSS software and the Linear Mixed Model ANOVA. Young subjects had significantly higher number of B cells (P<0.001), and this was particularly evident following vaccination (age*time interaction P<0.05). In contrast, older subjects had significantly more NK cells (P<0.001), but there was no change following vaccination. Young subjects had significantly more T cells compared to older subjects. After vaccination there was a slight increase in T cell number in the young cohort, but this did not reach statistical significance. Although total numbers of naı̈ve T cells were unaffected by ageing, numbers of CD8 + naı̈ve T cells in older subjects were significantly lower than those in the young subjects. There was no influence of the preand probiotic treatment on numbers of immune cell populations. Our findings confirman influence of ageing on innate and adaptive immunity, chiefly lower T cell and B cell numbers and elevated numbers of NK cells in older subjects. Although, there was no effect of treatment on the immune cell numbers, we are currently investigating the effects of the preand probiotic on activity of NK cells, B cells and T cells following vaccination. Proceedings of the Nutrition Society (2013), 72 (OCE1), E8 doi:10.1017/S0029665113000104