| 1. |
- Akter, S., et al.
(författare)
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The frequency of circulating integrin alpha 4 beta 7(+) cells correlates with protection against Helicobacter pylori infection in immunized mice
- 2019
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Ingår i: Helicobacter. - : Wiley. - 1083-4389 .- 1523-5378. ; 24:6
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Tidskriftsartikel (refereegranskat)abstract
- Background Chronic Helicobacter pylori infection is the cause of peptic ulcers in a subpopulation of individuals and a risk factor for the development of gastric cancer. A vaccine against H pylori infection can prevent the acquisition of the infection and protect against reinfections. Clinical trials to date evaluating the efficacy of H pylori vaccines in human challenge models have shown moderate to poor protection with difficulties in predicting efficacy. Thus, while further studies are needed to design an effective vaccine, we also need to find relevant correlates for vaccine efficacy. Objective To find immune correlates to vaccine efficacy, the frequencies of neutrophils, eosinophils and inflammatory monocytes and CD4(+) T-cell memory and mucosa homing integrin alpha 4 beta 7(+) cells were assessed by flow cytometry in the blood of mice after vaccination. Materials and Methods H pylori antigens and cholera toxin or the multiple mutant CT (mmCT) were administered via the sublingual (SL) and intragastric route (IG). The vaccinated mice were infected with H pylori strain SS1 bacteria, and colonization in the stomach and immune responses were evaluated. Results The H pylori vaccine was effective in reducing bacterial load in the stomach of mice and enhancing immune responses compared to unvaccinated infection controls. In the blood of mice after SL or IG route of vaccination, we observed changes in frequencies of innate and adaptive immune cell subsets compared to infection controls. Remarkably, the frequency of circulating mucosal homing alpha 4 beta 7(+)CD4(+) T cells after vaccination correlated with low bacterial load in the stomach of individual mice irrespective of the immunization route. Conclusions Our study shows that the innate and adaptive immune cell subsets can be measured in the blood after vaccination and that increased frequency of alpha 4 beta 7(+)CD4(+) in the blood after immunization could be used as a predictive marker for the efficacy of vaccine against H pylori infection.
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| 2. |
- Akhtar, M., et al.
(författare)
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Evaluation of the safety and immunogenicity of the oral inactivated multivalent enterotoxigenic Escherichia coli vaccine ETVAX in Bangladeshi adults in a double-blind, randomized, placebo-controlled Phase I trial using electrochemiluminescence and ELISA assays for immunogenicity analyses
- 2019
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X. ; 37:37, s. 5645-5656
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Tidskriftsartikel (refereegranskat)abstract
- The safety and immunogenicity of the second generation oral enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX, consisting of inactivated recombinant E. coli strains over-expressing the colonization factors (CFs) CFA/I, CS3, CS5 and CS6 and the heat labile toxoid LCTBA, were evaluated in Bangladeshi volunteers. To enable analysis of antibody responses against multiple vaccine antigens for subsequent use in small sample volumes from children, a sensitive electrochemiluminescence (ECL) assay for analysis of intestine-derived antibody-secreting cell responses using the antibodies in lymphocyte secretions (ALS) assay was established using Meso Scale Discovery technology. Three groups of Bangladeshi adults (n = 15 per group) received two oral doses of ETVAX with or without double mutant LT (dmLT) adjuvant or placebo in the initial part of a randomized, double-blind, placebo-controlled, age-descending, dose-escalation trial. CF- and LTB-specific ALS and plasma IgA responses were analyzed by ECL and/or ELISA. ETVAX was safe and well tolerated in the adults. Magnitudes of IgA ALS responses determined by ECL and ELISA correlated well (r = 0.85 to 0.98 for the five primary antigens, P < 0.001) and ECL was selected as the ALS readout method. ALS IgA responses against each of the primary antigens were detected in 87-100% of vaccinees after the first and in 100% after the second vaccine dose. Plasma IgA responses against different CFs and LTB were observed in 62-93% and 100% of vaccinees, respectively. No statistically significant adjuvant effect of dmLT on antibody responses to any antigen was detected, but the overall anti-genic breadth of the plasma IgA response tended to favor the adjuvanted vaccine when responses to 4 or more or 5 vaccine antigens were considered. Responses in placebo recipients were infrequent and mainly detected against single antigens. The promising results in adults supported testing ETVAX in descending age groups of children.
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| 3. |
- Akhtar, M., et al.
(författare)
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Kinetics of antibody-secreting cell and fecal IgA responses after oral cholera vaccination in different age groups in a cholera endemic country
- 2017
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X. ; 35:2, s. 321-328
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Tidskriftsartikel (refereegranskat)abstract
- Immune responses to oral enteric vaccines in children and infants may be influenced by factors such as age, previous priming with related microorganisms and breast feeding. In this study, we aimed to determine optimal time points to assess immune responses to oral enteric vaccines in different clinical specimens. This was done by investigating antibody secreting cell (ASC) and fecal antibody responses on different days after vaccination using the licensed oral cholera vaccine Dukoral, containing cholera toxin B-subunit (rCTB) and inactivated Vibrio cholerae bacteria, as a model vaccine. Two vaccine doses were given 2 weeks apart to infants (6-11 months), young children (12-18 months), toddlers (19 months-5 years) and adults in a cholera endemic country (Bangladesh). IgA ASC responses, as determined by the antibodies in lymphocyte supernatant (ALS) assay, plasma IgA and IgG responses and secretory IgA (SIgA) responses in extracts of fecal samples were evaluated 4/5 and 7 days after each vaccination. After the first vaccine dose, anti-CTB ALS IgA responses in adults and toddlers were high and comparable on day 5 and 7, while responses were low and infrequent in young children. After the second dose, highest ALS responses were detected on day 5 among the time points studied in all age groups and the responses declined until day 7. In contrast, plasma IgA and IgG anti-CTB responses were high both on day 5 and 7 after the second dose. Fecal SIgA responses in young children and infants were highest on day 7 after the second dose. Our results suggest that ASC/ALS responses to two doses of the oral cholera vaccine Dukoral and related oral vaccines should be analyzed earlier than previously recommended (day 7) at all ages. Fecal antibody responses should preferably be analyzed later than ASC/ALS responses to detect the highest antibody responses. (C) 2016 Elsevier Ltd. All rights reserved.
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| 4. |
- Cardeno, Ana, et al.
(författare)
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Activated T follicular helper-like cells are released into blood after oral vaccination and correlate with vaccine specific mucosal B-cell memory
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- T follicular helper (Tfh)-like cells with potent B-cell helping ability are mobilized into human circulation after parenteral vaccination and are generally held to reflect ongoing germinal center reactions. However, whether mucosal vaccination induces systemic Tfh responses and how such responses may relate to IgA production are unknown. We investigated the frequencies, phenotype and function of circulating Tfh-like CD4(+) CXCR5(+) T cells (cTfh) in adults receiving an oral inactivated enterotoxigenic Escherichia coli vaccine. Subjects were classified as vaccine responders or weak/non-responders based on their intestine-derived antibody-secreting cell (ASC) IgA responses to major vaccine antigens. Oral immunization induced significantly increased proportions of cTfh cells expressing the cTfh activation marker inducible costimulator (ICOS) in ASC responders, but not in weak/non-responders. Vaccination also enhanced the expression of IL-21, Th17 markers and integrin beta 7 by activated cTfh cells, supporting functionality and gut homing potential. cTfh cells promoted total and vaccine specific IgA production from cocultured B cells. Magnitudes of cTfh responses assessed within a week after primary vaccinations correlated with memory intestine-derived vaccine specific IgA responses 1-2 years later. We conclude that activated ICOS+ Tfh-like cells are mobilized into blood after oral vaccination and may be used as biomarkers of vaccine specific mucosal memory in humans.
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| 5. |
- Larena, Maximilian, et al.
(författare)
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Cholera toxin, and the related nontoxic adjuvants mmCT and dmLT, promote human Th17 responses via cyclic AMP-protein kinase A and inflammasome-dependent IL-1 signaling
- 2015
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 194:8, s. 3829-39
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Tidskriftsartikel (refereegranskat)abstract
- We have examined the molecular pathways involved in the adjuvant action of cholera toxin (CT) and two novel nontoxic molecules, multiple-mutated CT (mmCT) and double-mutant heat-labile toxin (dmLT) on human T cell responses. Human PBMCs or isolated monocytes were stimulated in vitro with CT, mmCT, or dmLT plus a polyclonal stimulus (staphylococcal enterotoxin B) or specific bacterial Ags, and effects on expression of cytokines and signaling molecules were determined. CT, mmCT, and dmLT strongly enhanced IL-17A and to a lesser extent IL-13 responses, but had little effect on IFN-gamma production or cell proliferation. Intracellular cytokine staining revealed that the enhanced IL-17A production was largely confined to CD4(+) T cells and coculture experiments showed that the IL-17A promotion was effectively induced by adjuvant-treated monocytes. Relative to CT, mmCT and dmLT induced at least 100-fold lower levels of cAMP, yet this cAMP was enough and essential for the promotion of Th17 responses. Thus, inhibition of cAMP-dependent protein kinase A was abolished, and stimulation with a cAMP analog mimicked the adjuvant effect. Furthermore, CT, mmCT, and dmLT induced IL-1beta production and caspase-1 activation in monocytes, which was associated with increased expression of key proinflammatory and inflammasome-related genes, including NLRP1, NLRP3, and NLRC4. Inflammasome inhibition with a specific caspase-1 inhibitor, or blocking of IL-1 signaling by IL-1 receptor antagonist, abrogated the Th17-promoting effect. We conclude that CT, mmCT, and dmLT promote human Th17 responses via cAMP-dependent protein kinase A and caspase-1/inflammasome-dependent IL-1 signaling.
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| 6. |
- Leach, Susannah, 1983, et al.
(författare)
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Cross-reactivity and avidity of antibody responses induced in humans by the oral inactivated multivalent enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX
- 2017
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X. ; 35:32, s. 3966-3973
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Tidskriftsartikel (refereegranskat)abstract
- We investigated whether the oral inactivated, multivalent enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX, consisting of four E. coli strains over-expressing the colonisation factors (CFs) CFA/I, CS3, CS5 and CS6, combined with the toxoid LCTBA, could induce cross-reactive antibodies to CFs related to the CFA/I and CS5 families. We also evaluated the avidity of vaccine induced antibodies against the toxoid and CFs. Cross-reactivity was analysed in mucosal (faecal and antibodies in lymphocyte supernatants, ALS) samples, and antibody avidity in serum and ALS samples, from two phase I trials: a primary vaccination study, where two oral doses of ETVAX were given the double mutant heat labile toxin (dmLT) adjuvant at a 2-week interval, and a booster vaccination study, where a single booster dose of ETVAX was given 13-23 months after primary vaccinations. We found that 65-90% of subjects who had responded to CFA/I in ALS or faecal specimens also developed cross-reactive antibodies to the related CFs tested, i.e. CS1, CS14 and CS17, and that approximately 80% of those responding to CS5 also responded to the closely related CS7. For subjects who had developed cross-reactive antibodies, the magnitudes of responses against vaccine CFs and related non-vaccine CFs were comparable. Using both a simple method of antibody avidity determination based on limiting antigen dilution, as well as a chaotropic ELISA method, we found that the avidity of serum and ALS antibodies to key vaccine antigens increased after a late booster dose compared to after primary vaccination. Our results suggest that the cross-reactive antibody responses against multiple CFs may result in expanded ETEC strain coverage of ETVAX and that repeated vaccinations induce vaccine-specific antibodies with increased binding capacity.
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| 7. |
- Lundgren, Anna, 1974, et al.
(författare)
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Induction of long term mucosal immunological memory in humans by an oral inactivated multivalent enterotoxigenic Escherichia coli vaccine
- 2016
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X. ; 34:27, s. 3132-3140
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Tidskriftsartikel (refereegranskat)abstract
- We have evaluated the capacity of an oral multivalent enterotoxigenic Escherichia call (ETEC) vaccine (MEV) to induce mucosal immunological memory. MEV consists of four inactivated E. coli strains over expressing the major colonization factors (CFs) CFA/I, CS3, CS5 and CS6 and the LTB-related toxoid LCTBA. Memory responses were analyzed by comparing the magnitudes and kinetics of intestine-derived antibody-secreting cell responses to a single dose of MEV in three groups of adult Swedish volunteers (n = 16-19 subjects per group) in a Phase I trial: non-immunized controls (I) and subjects who in a previous Phase I trial 13-23 months earlier had received two biweekly doses of MEV (II) or MEV + double mutant LT (dmLT) adjuvant (III). Responses against CFs and LTB were analyzed in antibodies in lymphocyte secretions (ALS) of blood mononuclear cells collected before (day 0) and 4/5 and 7 days after immunization. Specific circulating memory B cells present at the time of the single dose vaccination were also studied to determine if such cells may reflect mucosal memory. Considerably higher and significantly more frequent IgA ALS responses against all CFs and LTB were induced by the single vaccine dose in the previously immunized than in non-immunized volunteers. Furthermore, peak IgA ALS responses against all antigens were observed on days 4/5 in most of the previously immunized subjects whereas only a few previously non-vaccinated individuals responded before day 7. Priming with adjuvant did not influence memory responses. Circulating vaccine specific IgA memory B cells were not detected, whereas anti-toxin IgG memory B cells were identified 13-23 months after priming vaccination. We conclude that MEV induces functional mucosal immunological memory which remains at least 1-2 years. Furthermore, our results support that analysis of antibody-secreting cell responses after booster vaccination may be a useful approach to evaluate longstanding mucosal immunological memory in humans. Clinical trials registration: ISRCTN27096290.
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| 8. |
- Petridou, Evangelia, 1972-, et al.
(författare)
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If Crisis or War Comes : A Study of Risk Communication of Eight European Union Member States
- 2019
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Ingår i: Journal of International Crisis and Risk Communication Research. - : Nicholson School of Communication, UCF. - 2576-0025 .- 2576-0017. ; 2:2, s. 207-232
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Tidskriftsartikel (refereegranskat)abstract
- How do European Union (EU) member states communicate risks to their citizens? In this study, we define risk communication as the information provided by different levels of government to citizens regarding possible future crises to which the general public might be subjected. We seek to answer the following questions: Are there any patterns in the risk communication strategies among EU member states in terms of the sender of information, the message conveyed, the method used, and the intended audience? Finally, to what extent is the state involved in ensuring the safety of its citizens? To tackle these questions, we examine the risk communication strategy of eight countries: Sweden, Finland, Germany, England, France, Estonia, Greece, and Cyprus. Our data consist of governmental web sites, publications, campaigns, and other modes of communication, such as videos posted on YouTube, with questions centering on institutional actors, methods of delivery, content, and effectiveness. We find that the institutional architecture of risk communication aligns with the broad administrative system of each member state. Countries tend to focus on risks that are specific to their context, with Sweden and, to a lesser extent, Germany having a special focus on consequences and providing guidelines to the public on how to survive for a certain period of time in the absence of the state. Especially in Sweden, though the state is a salient actor in risk communication through the dissemination of information at the agency level, the state retreats while urging the resilient citizen to take control of his or her own crisis management.
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| 9. |
- Petridou, Evangelia, 1972-, et al.
(författare)
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Risk Communication : A Comparative Study of Eight EU Countries
- 2018
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Konferensbidrag (refereegranskat)abstract
- How do EU member states communicate risks to their citizens? In this study, we define risk communication as the information provided by different levels of government to citizens regarding possible future crises. The questions serving as departure points for this study are as follows: How is the administrative system for risk communication set up in the countries studied? How the different risk communication campaigns are (provided that they exist) embedded in the larger administrative context? How is risk communication strategy formulated in each country and what kind of threats are emphasized? In order to tackle these questions, we examine the risk communication strategy of eight countries: Sweden, Finland, Germany, England, France, Estonia, Greece and Cyprus. Our data consist of governmental web sites, publications, campaigns, as well as other modes of communication, such as videos posted on YouTube, with questions centering on institutional actors, methods of delivery, content, and effectiveness. We acknowledge that risk communication aims at supporting vulnerable populations and evening out imbalances, but at the same time we flesh out the power dimension of risk. In our analysis, we search for reproduction of norms and social inequality in risk communication practices. The results show that some patterns emerge regarding the way different EU countries convey information to the public, but they do not hold strictly to geography or administrative system. Digital media are the foremost vehicle of risk communication and the message generally conveyed is geared towards traditional, middle class households with the main language of the country as their first language. Volunteer organizations are present in all the countries in question, though not at the same degree. The conveyance of “self-protection” guidelines implicitly places the responsibility of protection to the individual. The results also show that in some countries, materiality has become more prevalent than the social dimension of risk in the message the public sector conveys, and that there is a move from focusing on risk to focusing on security.
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| 10. |
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