Catherine Maidens

Functional Characterization of Intracellular and Secreted Forms of a Truncated Hepatitis C Virus E2 Glycoprotein

ABSTRACT The E2 protein of hepatitis C virus (HCV) is believed to be a virion surface glycoprotein that is a candidate for inclusion in an antiviral vaccine. A truncated soluble version of E2 has recently been shown to interact with CD81, suggesting that this protein may be a component of the receptor for HCV. When expressed in eukaryotic cells, a significant proportion of E2 forms misfolded aggregates. To analyze the specificity of interaction between E2 and CD81, the aggregated and monomeric forms of a truncated E2 glycoprotein (E2661) were separated by high-pressure liquid chromatography and analyzed for CD81 binding. Nonaggregated forms of E2 preferentially bound CD81 and a number of conformation-dependent monoclonal antibodies (MAbs). Furthermore, intracellular forms of E2661 were found to bind CD81 with greater affinity than the extracellular forms. Intracellular and secreted forms of E2661 were also found to differ in reactivity with MAbs and human sera, consistent with differences in antigenicity. Together, these data indicate that proper folding of E2 is important for its interaction with CD81 and that modifications of glycans can modulate this interaction. Identification of the biologically active forms of E2 will assist in the future design of vaccines to protect against HCV infection.

Modulation of vaccine response by concomitant probiotic administration.

Evidence suggests that probiotic bacteria modulate both innate and adaptive immunity in the host, and in some situations can result in reduced severity of common illnesses, such as acute rotavirus infection and respiratory infections. Responses to vaccination are increasingly being used to provide high quality information on the immunomodulatory effects of dietary components in humans. The present review focuses on the effect of probiotic administration upon vaccination response. The majority of studies investigating the impact of probiotics on responses to vaccination have been conducted in healthy adults, and at best they show modest effects of probiotics on serum or salivary IgA titres. Studies in infants and in elderly subjects are very limited, and it is too early to draw any firm conclusions regarding the potential for probiotics to act as adjuvants in vaccination. Although some studies are comparable in terms of duration of the intervention, age and characteristics of the subjects, most differ in terms of the probiotic selected. Further well designed, randomized, placebo‐controlled studies are needed to understand fully the immunomodulatory properties of probiotics, whether the effects exerted are strain‐dependent and age‐dependent and their clinical relevance in enhancing immune protection following vaccination.

Increased Whole Grain Consumption Does Not Affect Blood Biochemistry, Body Composition, or Gut Microbiology in Healthy, Low-Habitual Whole Grain Consumers

BACKGROUND Whole-grain (WG) foods have been suggested to reduce the risk of cardiovascular disease, but studies are inconsistent and effects on cardiovascular risk markers are not clear. OBJECTIVE The objective of this study was to assess the impact of increasing WG consumption to at least 80 g/d on overall dietary intake, body composition, blood pressure (BP), blood lipids, blood glucose, gastrointestinal microbiology, and gastrointestinal symptoms in healthy, middle-aged adults with habitual WG intake <24 g/d. METHODS Eligible subjects [12 men, 21 women, aged 40-65 y, body mass index (BMI): 20-35 kg/m(2)] were identified through use of food frequency questionnaires and subsequently completed 3-day food diaries (3DFDs) to confirm habitual WG consumption. Subjects consumed diets high in WG (>80 g/d) or low in WG [<16 g/d, refined-grain (RG) diet] in a crossover study with 6-wk intervention periods separated by a 4-wk washout. Adherence was achieved by specific dietary advice and provision of a range of cereal food products. The 3DFDs, diet compliance diaries, and plasma alkylresorcinols were used to verify compliance. RESULTS During the WG intervention, consumption increased from 28 g/d to 168 g/d (P < 0.001), accompanied by an increase in plasma alkylresorcinols (P < 0.001) and total fiber intake (P < 0.001), without any effect on energy or other macronutrients. Although there were no effects on studied variables, there were trends toward increased 24-h fecal weight (P = 0.08) and reduction in body weight (P = 0.10) and BMI (P = 0.08) during the WG intervention compared with the RG period. CONCLUSION A combination of dietary advice and provision of commercially available food items enabled subjects with a low-moderate habitual consumption of WG to substantially increase their WG intake, but there was little effect on blood biochemical markers, body composition, BP, fecal measurements, or gut microbiology. This trial was registered at www.controlled-trials.com as ISRCTN36521837.

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.

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.

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.

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