Alcohol-related liver disease (ALD) remains a leading indication for liver transplantation and a major cause of alcohol-attributable deaths worldwide. The molecular events driving extracellular matrix (ECM) accumulation are incompletely understood. In this study, we aimed to investigate stage-specific gene expression signatures in ALD. Liver biopsies from 50 adults with prior alcohol overuse were selected: No fibrosis (controls (F0), n = 10), mild/moderate fibrosis (F1–F2, n = 19), and advanced fibrosis/cirrhosis (F3–F4, n = 21). We performed multiplexed targeted profiling of 760 mRNAs, followed by analysis of differentially expressed genes (DEGs) and gene set enrichment analysis. Selected targets were validated on the protein level using immunohistochemistry. Mild/moderate fibrosis versus controls showed 80 DEGs (p < 0.01), 63 of which were downregulated. MLXIPL and FURIN, both involved in glucose and lipid metabolism, were downregulated. Pathways involved in ECM formation were enriched. Advanced fibrosis vs. controls showed 187 DEGs (p < 0.01), of which 94 were upregulated. These included fibrogenic and inflammatory mediators such as TGFB1, COL1A1/2, TIMP1, LGALS3, and S100A4. Genes involved in fatty acid, steroid, and lipid metabolism were significantly repressed. Advanced versus mild/moderate fibrosis showed 211 DEGs (p < 0.01), with an increase in TGF-β-driven ECM remodeling and inhibition of lipid and fatty-acid metabolism pathways. LGALS3 and S100A4 mRNA levels correlated with protein expression (R ≥ 0.41, p < 0.01). ALD is characterized by early downregulation of metabolic genes and upregulation of ECM formation, followed by coordinated induction of the TGF-β-centered fibrogenic pathway and further suppression of metabolic pathways. We identified stage-specific molecular alterations associated with ALD progression and LGALS3 and S100A4 as candidate biomarkers.

Long-lived immunoglobulin (Ig) E responses against innocuous environmental and dietary antigens (Ags) are maintained by an IgG1-dominant memory B cell (MBC) compartment primed for IL-4 responsiveness. In this work, we investigated the plasticity of the MBC compartment fated for IgE class switch recombination upon Ag re-exposure. Antibody-mediated IL-4R( blockade augmented the germinal center response and uncovered an IL-4/IL-13 dependency within the type 2 memory B cell (MBC2) skewed phenotype. In the absence of IL-4/IL-13 signaling during the recall response, a long-lived Ag-specific IgG2c MBC population emerged, shifting the MBC response away from a type 2 phenotype and towards type 1. The emergence of this IgG2c response was dependent on IFN-( signaling and arose from both unswitched and class-switched Ag-specific B cells in vivo. We further demonstrated that a type 1-polarizing adjuvant can augment the redirection of type 2-polarized class-switched MBCs, suggesting with the correct cues pathogenic MBCs can be functionally reprogrammed. One Sentence Summary B cell responses to allergens can be reprogrammed away from a pathogenic fate through IL-4/IL-13 signaling blockade.

Introduction:Airway mucosa represents the main entry point for several human pathogens, and as such vaccines against respiratory diseases should ideally elicit protective immune responses in the airways. We have previously reported two immunomodulatory adjuvants based on non-toxic derivatives of Cholera toxin (CT), namely mmCT and CTB-CpG with strong ability to mount mucosal immune responses. Methods:Herein, we aimed to pinpoint the potential of prime-boost immunization approaches using the fusion-protein based Mycobacterium tuberculosis subunit vaccine candidate H56 as a model antigen, combined with adjuvants CAF01, mmCT, and CTB-CpG in mice. This included a parenteral H56+CAF01 priming followed by an intranasal boost with H56+CAF01, H56+mmCT, or H56+CTB-CpG, compared with repeated homologous intranasal administrations of H56 with each adjuvant. Results:We observed that a parenteral prime with H56+CAF01 followed by an intranasal H56+CTB-CpG booster immunization triggered a Th1-skewed immune response. Conversely, combining the parenteral H56+CAF01 prime with an intranasal H56+mmCT boost resulted in a mixed Th1/Th17-skewed immune response. Notably, the latter combination also engendered anamnestic, long-lived T-cell responses in the lungs which homologous intranasal H56+mmCT immunizations failed to induce. Discussion:These results suggest that an immunization regimen consists of parenteral priming with H56+CAF01 followed by an airway boosting with H56 protein and mucosal adjuvants holds promise in mounting combined systemic and mucosal immune responses to Mycobacterium tuberculosis, and as such warrants further exploration. Given the rising interest in mucosal vaccines for respiratory pathogens, these findings offer an important immunological framework for future translational studies.

BACKGROUND:People with tuberculosis who complete treatment remain at risk of recurrent disease. The vaccine H56:IC31 has been shown to be safe and immunogenic in phase 1 and 2 studies, but whether it can reduce the risk of tuberculosis recurrence is unknown. METHODS:In a double-blind, randomised, placebo-controlled, phase 2b trial in South Africa (five clinical trial sites) and Tanzania (one clinical trial site), we enrolled participants aged 18-60 years, without HIV, who had completed more than 5 months (22 weeks) of treatment for drug-susceptible pulmonary tuberculosis. During trial screening (≤7 days after starting treatment), two sputum samples were obtained and frozen for later comparison to recurrent isolates by whole-genome sequencing (WGS). Eligible participants were randomly assigned (1:1; block size of four) to receive two intramuscular doses in the deltoid, 56 days apart, of H56:IC31 or placebo. After the first dose of H56:IC31 or placebo, participants were followed up until study day 421 (1 year after the second dose) and checked at each visit for tuberculosis signs and symptoms. If tuberculosis was suspected, two sputum samples were obtained: one sample was tested by automated molecular test (Xpert MTB/RIF Ultra) and sent for liquid culture; and the other sample was stored frozen for later analysis by whole-genome sequencing (WGS). At the last visit (day 421), two sputum samples were obtained from all sputum-productive participants, regardless of symptoms, to detect cases of asymptomatic tuberculosis. The primary endpoint was culture-confirmed recurrent pulmonary tuberculosis (due to relapse with the same strain, reinfection by a different strain, or indeterminate) occuring during the period starting at day 70 (14 days after the second dose) and ending on day 421 (1 year after the second dose). Vaccine efficacy against recurrent tuberculosis was derived from Cox proportional hazards models. Secondary endpoints included vaccine efficacy to prevent tuberculosis relapse or reinfection independently, as differentiated by WGS, and safety and immunogenicity outcomes (H56-specific CD4 T-cell responses and humoral anti-H56 IgG responses). Primary analysis of vaccine efficacy was based on modified intention-to-treat (mITT), in all randomly assigned participants except those with tuberculosis disease recurrence or who withdrew before day 70 (or 14 days after the second dose for those who received both doses). Safety was assessed in all randomly assigned participants who received at least one dose of vaccine or placebo. The trial was registered with ClinicalTrials.gov, NCT03512249, and is complete. FINDINGS:831 participants (mean age 34·7 years [SD 11·1]; 229 [28%] female and 602 [72%] male; 549 [66%] Black) were enrolled from Jan 31, 2019, to Jan 20, 2022; 415 participants were randomly assigned to receive H56:IC31 and 416 to receive placebo. Follow-up was completed by March 20, 2023 (mean follow-up duration 410·1 days [SD 82·8]). In the primary mITT analysis, recurrent tuberculosis occurred in 23 of 400 participants in the H56:IC31 group (12 relapses, eight reinfections, and three indeterminate); and in 14 of 406 in the placebo group (six relapses, seven reinfections, and one indeterminate). Vaccine efficacy for prevention of recurrence was -73·8% (95% CI -246·9 to 9·8; p=0·10). Vaccine efficacy for prevention of relapse was -116·1% (-522·2 to 16·3; p=0·11) and for prevention of reinfection was -21·1% (-245·3 to 56·5; p=0·71). 2 weeks after the planned second dose, H56:IC31 had significantly increased the frequencies of H56-specific CD4 T cells expressing interferon-γ, tumour necrosis factor, interleukin (IL)-2, or IL-17 in vaccinees (median percentage of CD4 T cells, 0·35% [IQR 0·19 to 0·57]) compared with placebo (0·11% [0·09 to 0·23]; p<0·0001). H56-specific IgG responses were significantly higher in H56:IC31 recipients (median arbitrary units per mL, 6·84 [IQR 1·64 to 32·8]) than in placebo recipients (1·94 [1·05 to 3·86]; p<0·0001). A greater proportion of H56:IC31 recipients had mild-to-moderate injection site reactions than placebo recipients (165 [40%] of 415 vs 78 [19%] of 416). No treatment-related serious adverse events were reported. Two participants who received H56:IC31 and six who received placebo died. INTERPRETATION:Vaccination with H56:IC31 at treatment completion for pulmonary tuberculosis did not reduce the risk of recurrent disease. H56:IC31 was well tolerated and immunogenic but might have increased the risk of relapses by endogenous strains. FUNDING:The European and Developing Countries Clinical Trials Partnership (EDCTP2) supported by the EU (grant number RIA2016V-1631, POR TB consortium). Additional funding to support completion of the trial was provided by the Statens Serum Institut, Aurum Institute, and the South African Tuberculosis Vaccine Initiative.

Background H56:IC31 is a candidate vaccine against tuberculosis (TB) with the potential to reduce TB recurrence rate. It is thus important for future clinical trials to demonstrate safety and immunogenicity of H56:IC31 in individuals treated for TB. Methods Twenty-two adults confirmed to be Mycobacterium tuberculosis negative (by 2 GeneXpert tests or 2 sputum cultures) after 4-5 months of TB treatment, and not more than 28 days after completion of TB treatment, were randomized to receive 2 doses of H56:IC31 (5 mg H56:500 nmol IC31; n = 16) or placebo (n = 6) 56 days apart. Participants were followed for 420 days for safety and immunogenicity. Results H56:IC31 vaccination was associated with an acceptable safety profile, consisting mostly of mild self-limited injection site reactions. No serious adverse events or vaccine-related severe adverse events were reported. H56:IC31 induced a CD4(+) T-cell response for Ag85B and ESAT-6, with ESAT-6 being immunodominant, which persisted through 6 months after the last vaccination. There was some evidence of CD8(+) T-cell responses for both Ag85B and ESAT-6, but to a lesser extent than CD4(+) responses. Conclusions H56:IC31 was associated with an acceptable safety profile, and induced a predominant CD4(+) T-cell response, in adults recently treated for drug-susceptible, uncomplicated pulmonary TB.

BackgroundThere is no vaccine against the major global pathogen Chlamydia trachomatis; its different serovars cause trachoma in the eye or chlamydia in the genital tract. We did a clinical trial administering CTH522, a recombinant version of the C trachomatis major outer membrane molecule, in different dose concentrations with and without adjuvant, to establish its safety and immunogenicity when administered intramuscularly, intradermally, and topically into the eye, in prime-boost regimens.MethodsCHLM-02 was a phase 1, double-blind, randomised, placebo-controlled trial at the National Institute for Health Research Imperial Clinical Research Facility, London, UK. Participants were healthy men and non-pregnant women aged 18–45 years, without pre-existing C trachomatis genital infection. Participants were assigned into six groups by the electronic database in a pre-prepared randomisation list (A–F). Participants were randomly assigned (1:1:1:1:1) to each of the groups A–E (12 participants each) and 6 were randomly assigned to group F. Investigators were masked to treatment allocation. Groups A–E received investigational medicinal product and group F received placebo only. Two liposomal adjuvants were compared, CAF01 and CAF09b. The groups were intramuscular 85 μg CTH522-CAF01, or placebo on day 0 and two boosters or placebo at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (A); intramuscular 85 μg CTH522-CAF01, two boosters at day 28 and 112 with additional topical ocular administration of CTH522, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (B); intramuscular 85 μg CTH522-CAF01, two boosters at day 28 and 112 with additional intradermal administration of CTH522, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (C); intramuscular 15 μg CTH522-CAF01, two boosters at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (D); intramuscular 85 μg CTH522-CAF09b, two boosters at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (E); intramuscular placebo (F). The primary outcome was safety; the secondary outcome (humoral immunogenicity) was the percentage of trial participants achieving anti-CTH522 IgG seroconversion, defined as four-fold and ten-fold increase over baseline concentrations. Analyses were done as intention to treat and as per protocol. The trial is registered with ClinicalTrials.gov, NCT03926728, and is complete.FindingsBetween Feb 17, 2020 and Feb 22, 2022, of 154 participants screened, 65 were randomly assigned, and 60 completed the trial (34 [52%] of 65 women, 46 [71%] of 65 White, mean age 26·8 years). No serious adverse events occurred but one participant in group A2 discontinued dosing after having self-limiting adverse events after both placebo and investigational medicinal product doses. Study procedures were otherwise well tolerated; the majority of adverse events were mild to moderate, with only seven (1%) of 865 reported as grade 3 (severe). There was 100% four-fold seroconversion rate by day 42 in the active groups (A–E) and no seroconversion in the placebo group. Serum IgG anti-CTH522 titres were higher after 85 μg CTH522-CAF01 than 15 μg, although not significantly (intention-to-treat median IgG titre ratio groups A–C:D=5·6; p=0·062), with no difference after three injections of 85 μg CTH522-CAF01 compared with CTH522-CAF09b (group E). Intradermal CTH522 (group C) induced high titres of serum IgG anti-CTH522 neutralising antibodies against serovars B (trachoma) and D (urogenital). Topical ocular CTH522 (group B) at day 28 and 112 induced higher total ocular IgA compared with baseline (p<0·001). Participants in all active vaccine groups, particularly groups B and E, developed cell mediated immune responses against CTH522.InterpretationCTH522, adjuvanted with CAF01 or CAF09b, is safe and immunogenic, with 85 μg CTH522-CAF01 inducing robust serum IgG binding titres. Intradermal vaccination conferred systemic IgG neutralisation breadth, and topical ocular administration increased ocular IgA formation. These findings indicate CTH522 vaccine regimens against ocular trachoma and urogenital chlamydia for testing in phase 2, clinical trials.FundingThe EU Horizon Program TRACVAC.

Sublingual allergen immunotherapy (SLIT) is an emerging treatment option for allergic asthma and a potential disease-modifying strategy for asthma prevention. The key cellular events leading to such long-term tolerance remain to be fully elucidated. We administered prophylactic SLIT in a mouse model of house dust mite (HDM)-driven allergic asthma. HDM extract was sublingually administered over 3 weeks followed by intratracheal sensitization and intranasal challenges with HDM. Prophylactic SLIT prevented allergic airway inflammation and hyperreactivity with a low lab-to-lab variation. The HDM-specific T helper (Th)2 (cluster of differentiation 4 Th) response was shifted by SLIT toward a regulatory and Th17 response in the lung and mediastinal lymph node. By using Derp1-specific cluster of differentiation 4+ T cells (1-DER), we found that SLIT blocked 1-DER T cell recruitment to the mediastinal lymph node and dampened IL-4 secretion following intratracheal HDM sensitization. Sublingually administered Derp1 protein activated 1-DER T cells in the cervical lymph node via chemokine receptor7+ migratory dendritic cells (DC). DCs migrating from the oral submucosa to the cervical lymph node after SLIT-induced Foxp3+ regulatory T cells. When mice were sensitized with HDM, prior prophylactic SLIT increased Derp1 specific regulatory T cells (Tregs) and lowered Th2 recruitment in the lung. By using Foxp3-diphtheria toxin receptor mice, Tregs were found to contribute to the immunoregulatory prophylactic effect of SLIT on type 2 immunity. These findings in a mouse model suggest that DC-mediated functional Treg induction in oral mucosa draining lymph nodes is one of the driving mechanisms behind the disease-modifying effect of prophylactic SLIT.

Background : Sublingual immunotherapy (SLIT) is a safe and effective treatment for allergic diseases. While it is generally accepted that SLIT-induced tolerance is allergen-specific, it has been suggested that SLIT may also prevent the development of new sensitizations or even confer protection towards unrelated allergens. Methods : In the present study we applied murine models of systemic sensitization to investigate allergen-specific as well as bystander tolerance induced by SLIT. Results : We demonstrate that prophylactic SLIT with Phleum pratense (Phl p) extract leads to allergen-specific systemic tolerance in mice and that this tolerance is more efficiently induced via the sublingual route compared to the peroral and intranasal routes. In addition to antigen-specific tolerance, SLIT with Phl p extract also induced bystander tolerance, as demonstrated by downregulated reactivity towards the unrelated protein ovalbumin (OVA). Bystander tolerance was dependent on the presence of Phl p extract during OVA sensitization, indicating that co-exposure is critical for the effect. Finally, by assessing the ability of different antigens (allergens as well as non-allergens) to induce bystander tolerance, we observed that the ability to induce bystander tolerance correlated with the immunogenicity of a given protein. Conclusion : Prophylactic SLIT with immunogenic proteins is able to prevent the spred of sensitizations to other antigens. This supports that allergy immunotherapy, used as primary prevention, may prevent development of new sensitizations to additional allergens and thereby influence the allergic march.

Background Hypersensitivity to house dust mite (HDM) allergens is a common cause of allergic asthma symptoms and can be effectively treated with allergy immunotherapy (AIT). Objective To investigate whether genetic and type 2 (T2) inflammatory biomarkers correlate with disease severity in subjects with allergic asthma, and whether this can be modified by AIT. Methods MITRA ( NCT01433523 ) was a phase III, randomised, double-blind, placebo-controlled trial of HDM sublingual immunotherapy (SLIT)-tablets in adults with HDM allergic asthma. Post hoc analyses of the study population (N=742) evaluated associations between T2 inflammatory (blood eosinophils, eosinophil cationic protein (ECP), total IgE and tryptase) and genetic (single-nucleotide polymorphisms, SNP) biomarkers (n=582) for the primary study endpoint (time to first moderate/severe asthma exacerbation). SNP associations were verified in HDM-positive subgroup from an independent 3-year Severe Asthma Research Programme (SARP3) subject cohort. Results An increased asthma exacerbation risk in subjects homozygous for SNP rs7216389 (chromosomal locus 17q12-21) was reduced (p = 0.037) by treatment with HDM SLIT (HR=0.37 (95% CI 0.22 to 0.64), p<0.001). The associations between exacerbation risk and 17q12-21 SNPs were replicated in the SARP3 HDM-positive subgroup. High levels of T2 biomarkers were associated with increased risk of asthma exacerbations in the placebo group. HDM SLIT-tablet treatment reduced this risk (blood eosinophils: HR=0.50 (95% CI 0.30 to 0.85); ECP: HR=0.45 (95% CI 0.29 to 0.87); tryptase: HR=0.45 (95% CI 0.25 to 0.80)). The treatment effect was higher (p = 0.006) for subjects with a higher number of elevated T2 biomarkers. Conclusions HDM SLIT-tablet AIT is efficacious in HDM-sensitised asthma subjects with a genetic asthma predisposition and/or an underlying T2 endotype. Trial registration number NCT01433523 .

We report a case of Zika virus (ZIKV) infection in a pregnant woman from Denmark who traveled to Thailand during her first trimester. Late in the second trimester, severe microcephaly was diagnosed in the fetus, and ZIKV infection was confirmed. Travelers and clinicians should be aware of ongoing ZIKV risk in Thailand.

Background Chlamydia trachomatis (CT) Major Outer Membrane Protein (MOMP) holds a neutralising epitope in the Variable Domain 4 (VD4), and this region ' s immune dominance during infection is well known. This study aimed to assess the antibody response induced after infection and compare it for speci fi city and functionality to the response following vaccination with the vaccine CTH522, which contains VD4 ' s from serovars D, E, F, and G. Methods We assessed the antibody epitopes in MOMP by a high density peptide array. Furthermore, the role of the VD4 epitope in neutralisation was explored by competitive inhibition experiments with a fusion protein holding the neutralising VD4 linear epitope. This was done in two independent groups: 1) MOMP seropositive individuals infected with CT (n = 10, from case - control study) and 2) CTH522/CAF (R) 01-vaccinated females (n = 14) from the CHLM-01 clinical trial. Findings We identi fi ed the major antigenic regions in MOMP as VD4 and the conserved region just before VD3 in individuals infected with CT. The same regions, with the addition of VD1, were identi fi ed in vaccine recipients. Overall, the VD4 peptide responses were uniform in vaccinated individuals and led to inhibition of infection in vitro in all tested samples, whereas the VD4 responses were more heterogenous in individuals infected with CT, and only 2 out of 10 samples had VD4-mediated neutralising antibody responses. Interpretation These data provide insights into the role of antibodies against MOMP VD4 induced after infection and vaccination, and show that their functionality differs. The induction of functional VD4-speci fi c antibodies in vaccine recipients mimics previous results from animal models. 2024;104: Published https://doi.org/10. 1016/j.ebiom.2024. 105140

BackgroundDenmark possesses an exceptional historical data collection on tuberculosis (TB) from 1876 to the present, providing a unique opportunity to assess TB epidemiology over 147 years in Denmark.AimOur aim was to describe the TB disease burden in Denmark in relation to historical events, living conditions and health interventions during the past 147 years.MethodsWe performed a nationwide register-based ecological study including all persons with TB in Denmark from 1876 through 2022, correlating the TB incidence to social, economic and health indicators.ResultsIn Denmark, the overall TB incidence and mortality declined markedly over the past 147 years, only marginally influenced by specific TB interventions such as sanatoria, Bacillus Calmette-Guèrin (BCG) vaccination, mass screenings and antibiotics. Parallel to this decline, the country experienced improved living conditions, as illustrated by decreased infant mortality and increased life expectancy and wealth. In 1978, Denmark became a low-incidence country for TB with risk groups predominantly affected, and with a continuous change in demographics towards fewer Danish-born cases and relatively more migrant cases.ConclusionsThe decline over time in TB incidence and mortality in Denmark preceded specific TB interventions and can, first of all, be attributed to improved living conditions. TB has now become a rare disease in Denmark, predominantly occurring in particular risk groups. Future elimination of TB will require a combination of specific health interventions in these risk groups combined with a continued focus on improving socioeconomic status and living conditions.

Allergen-specific immunoglobulin E (IgE) antibodies mediate pathology in diseases such as allergic rhinitis and food allergy. Memory B cells (MBCs) contribute to circulating IgE by regenerating IgE-producing plasma cells upon allergen encounter. Here, we report a population of type 2–polarized MBCs defined as CD23 hi , IL-4Rα hi , and CD32 low at both the transcriptional and surface protein levels. These MBC2s are enriched in IgG1- and IgG4-expressing cells while constitutively expressing germline transcripts for IgE. Allergen-specific B cells from patients with allergic rhinitis and food allergy were enriched in MBC2s. Furthermore, MBC2s generated allergen-specific IgE during sublingual immunotherapy, thereby identifying these cells as a major reservoir for IgE. The identification of MBC2s provides insights into the maintenance of IgE memory, which is detrimental in allergic diseases but could be beneficial in protection against venoms and helminths.

ObjectivesThis study aimed to analyze mortality, risk factors, and causes of death among people with tuberculosis (TB).MethodsThis is a population-based cohort study with patients with TB ≥18 years notified from 1990 to 2018 in Denmark, compared with sex- and age-matched controls. Mortality was assessed in Kaplan–Meier models and risk factors for death were estimated in Cox proportional hazards models.ResultsOverall mortality was twofold higher among people with TB compared with controls up to 15 years after TB diagnosis (hazard ratio [HR]: 2.18, 95% confidence interval [CI]: 2.06-2.29, P <0.0001). Danes with TB were three times more likely to die than migrants (adjusted HR: 3.13, 95% CI: 2.84-3.45, P <0.0001). Risk factors for death included living alone, being unemployed, having low income, and comorbidities such as mental illness with substance abuse, lung diseases, hepatitis, and HIV. TB was the most common cause of death (21%), followed by chronic obstructive pulmonary disease (7%), lung cancer (6%), alcoholic liver disease (5%), and mental illness with substance abuse (4%).ConclusionPeople with TB had substantially inferior survival up to 15 years after TB diagnosis, in particular, socially disadvantaged Danes with TB with specific comorbidities. This may reflect unmet needs for enhanced treatment of other medical/social conditions during TB treatment.

Allergen-specific IgE antibodies mediate allergic pathology in diseases such as allergic rhinitis and food allergy. Memory B cells (MBCs) contribute to circulating IgE by regenerating IgE-producing plasma cells upon allergen encounter. We report a population of type 2 polarized MBCs defined as CD23 hi , IL-4Rα hi , CD32 low at the transcriptional and surface protein levels. These “MBC2s” are enriched in IgG1 and IgG4-expressing cells, while constitutively expressing germline transcripts for IgE. Allergen-specific B cells from patients with allergic rhinitis and food allergy were enriched in MBC2s. MBC2s generated allergen specific-IgE during sublingual immunotherapy, thereby identifying these cells as the primary reservoir of IgE. The identification of MBC2s provides insights into the maintenance of IgE memory, which is detrimental in allergic diseases, but which could be beneficial in protection against venoms and helminths. One-Sentence Summary Identification of a novel memory B cell subset which holds allergen specific IgE memory.

IntroductionC-type lectin receptor (CLR) agonists emerged as superior inducers of primary B cell responses in early life compared with Toll-like receptor (TLR) agonists, while both types of adjuvants are potent in adults.MethodsHere, we explored the mechanisms accounting for the differences in neonatal adjuvanticity between a CLR-based (CAF®01) and a TLR4-based (GLA-SE) adjuvant administered with influenza hemagglutinin (HA) in neonatal mice, by using transcriptomics and systems biology analyses.ResultsOn day 7 after immunization, HA/CAF01 increased IL6 and IL21 levels in the draining lymph nodes, while HA/GLA-SE increased IL10. CAF01 induced mixed Th1/Th17 neonatal responses while T cell responses induced by GLA-SE had a more pronounced Th2-profile. Only CAF01 induced T follicular helper (Tfh) cells expressing high levels of IL21 similar to levels induced in adult mice, which is essential for germinal center (GC) formation. Accordingly, only CAF01- induced neonatal Tfh cells activated adoptively transferred hen egg lysozyme (HEL)-specific B cells to form HEL+ GC B cells in neonatal mice upon vaccination with HEL-OVA.DiscussionCollectively, the data show that CLR-based adjuvants are promising neonatal and infant adjuvants due to their ability to harness Tfh responses in early life.