Consecutive BNT162b2 mRNA vaccination induces short-term epigenetic memory in innate immune cells

BNT162b2 mRNA vaccine elicits robust virus-specific antibodies but poor cross-protective CD8+ memory T cell responses in adolescents with type 1 diabetes

BACKGROUND

COVID-19 mRNA vaccines have demonstrated 95 % efficacy in the general population. However, their immunogenicity in adolescents with Type 1 Diabetes (T1D), who exhibit weaken immune responses, remains insufficiently explored.

METHODS

Longitudinal analysis of innate immune responses following PRR-agonists and BNT162b2 vaccine stimulations, along with S-specific antibody responses, memory T cell recall responses, and RNA-sequencing were assessed in eight T1D adolescents and 16 healthy controls at six different timepoints.

RESULTS

After BNT162b2 vaccination, T1D adolescents produced SARS-CoV-2-specific binding and neutralizing antibodies (Nabs) comparable to healthy controls. Lower pre-vaccination blood HbA1c level correlated with higher antibody responses among T1D adolescents. However, they exhibited impaired TLR9-induced B cells and the first vaccine-induced monocyte activation. These differences were supported by transcriptomic analysis, which revealed the impairment in innate immune-related signatures both before and after vaccination. One year post-second vaccination, T1D adolescents demonstrated compromised cross-protection of T cell against BA.1 compared to healthy controls, which correlated with impaired innate immune responses identified in this study.

CONCLUSION

This study reveals that while T1D adolescents vaccinated with the BNT162b2 vaccine develop robust S-specific antibodies, their cross-protective T cell responses are suboptimal.

Boosting effect of high-dose influenza vaccination on innate immunity among elderly

BACKGROUNDThe high-dose quadrivalent influenza vaccine (QIV-HD) showed superior efficacy against laboratory-confirmed illness compared with the standard-dose quadrivalent influenza vaccine (QIV-SD) in randomized controlled trials with the elderly. However, specific underlying mechanism remains unclear.METHODSThis phase IV randomized controlled trial compared early innate responses induced by QIV-HD and QIV-SD in 59 individuals aged > 65 years. Systemic innate cells and gene signatures at day 0 (D0) and D1 as well as hemagglutinin inhibition antibody (HIA) titers at D0 and D21 after vaccination were assessed.RESULTSQIV-HD elicited robust humoral response with significantly higher antibody titers and seroconversion rates than QIV-SD. At D1 after vaccination, QIV-HD recipients showed significant reduction in innate cells, including conventional DCs and NK cells, compared with QIV-SD, correlating with significantly increased HIA titers at D21. Blood transcriptomic analysis revealed greater amplitude of gene expression in the QIV-HD arm, encompassing genes related to innate immune response, IFNs, and antigen processing and presentation, and correlated with humoral responses. Interestingly, comparative analysis with a literature dataset from young adults vaccinated with influenza standard-dose vaccine highlighted strong similarities in gene expression patterns and biological pathways with the elderly vaccinated with QIV-HD.CONCLUSIONQIV-HD induces higher HIA titers than QIV-SD, a youthful boost of the innate gene expression significantly associated with high HIA titers.TRIAL REGISTRATIONEudraCT no. 2021-004573-32.

Altered baseline immunological state and impaired immune response to SARS-CoV-2 mRNA vaccination in lung transplant recipients

The effectiveness of COVID-19 mRNA vaccines is diminished in organ transplant patients. Using a multi-omics approach, we investigate the immunological state of lung transplant (LTX) recipients at baseline and after SARS-CoV-2 mRNA vaccination compared to healthy controls (HCs). LTX patients exhibit a baseline immune profile resembling severe COVID-19 and sepsis, characterized by elevated pro-inflammatory cytokines (e.g., EN-RAGE [also known as S100A12], interleukin [IL]-6), reduced human leukocyte antigen (HLA)-DR expression on monocytes and dendritic cells, impaired cytokine production, and increased plasma microbial products. Single-cell RNA sequencing identifies an enriched monocyte cluster in LTX patients marked by high S100A family expression and reduced cytokine and antigen presentation genes. Post vaccination, LTX patients show diminished antibody, B cell, and T cell responses, along with blunted innate immune signatures. Integrative analysis links these altered baseline immunological features to impaired vaccine responses. These findings provide critical insights into the immunosuppressed condition of LTX recipients and their reduced vaccine-induced adaptive and innate immune responses.

Persistent epigenetic memory of SARS-CoV-2 mRNA vaccination in monocyte-derived macrophages

Immune memory plays a critical role in the development of durable antimicrobial immune responses. How precisely mRNA vaccines train innate immune cells to shape protective host defense mechanisms remains unknown. Here we show that SARS-CoV-2 mRNA vaccination significantly establishes histone H3 lysine 27 acetylation (H3K27ac) at promoters of human monocyte-derived macrophages, suggesting epigenetic memory. However, we found that two consecutive vaccinations were required for the persistence of H3K27ac, which matched with pro-inflammatory innate immune-associated transcriptional changes and antigen-mediated cytokine secretion. H3K27ac at promoter regions were preserved for six months and a single mRNA booster vaccine potently restored their levels and release of macrophage-derived cytokines. Interestingly, we found that H3K27ac at promoters is enriched for G-quadruplex DNA secondary structure-forming sequences in macrophage-derived nucleosome-depleted regions, linking epigenetic memory to nucleic acid structure. Collectively, these findings reveal that mRNA vaccines induce a highly dynamic and persistent training of innate immune cells enabling a sustained pro-inflammatory immune response.

The immune memory of innate immune systems

Immune memory has long been considered a function specific to adaptive immune systems; however, adaptive immune memory alone has not fully explained the mechanism by which vaccines exert their protective effects against nontarget pathogens. Recently, trained immunity, in which human monocytes vaccinated with bacillus Calmette-Guérin become highly responsive to pathogens other than Mycobacterium tuberculosis, has been reported. However, a phenomenon called endotoxin tolerance is also known, in which monocyte responsiveness is attenuated after the first lipopolysaccharide stimulation. These phenomena represent an altered innate immune response after the initial exposure to the stimulus, indicating that memories are formed in the innate immune system. In this review, we discuss trained immunity and endotoxin tolerance, known as innate immune memory, and innate immune memory formation by mRNA vaccines, which have been newly used in the coronavirus disease 2019 (COVID-19) pandemic and are considered important vaccine modalities in the future.

An LNP-mRNA vaccine modulates innate cell trafficking and promotes polyfunctional Th1 CD4+ T cell responses to enhance BCG-induced protective immunity against Mycobacterium tuberculosis

BACKGROUND

Mycobacterium tuberculosis remains the largest infectious cause of mortality worldwide, even with over a century of widespread administration of the only licenced tuberculosis (TB) vaccine, Bacillus Calmette-Guérin (BCG). mRNA technology remains an underexplored approach for combating chronic bacterial infections such as TB.

METHODS

We have developed a lipid nanoparticle (LNP)-mRNA vaccine, termed mRNACV2, encoding for the M. tuberculosis CysVac2 fusion protein, which we have previously formulated as an adjuvanted subunit vaccine. This LNP-mRNA vaccine was administered intramuscularly to female C57BL/6 mice as a standalone vaccine or as booster to BCG to assess immunogenicity and efficacy of the construct.

FINDINGS

Vaccination with mRNACV2 induced high frequencies of polyfunctional, antigen-specific Th1 CD4+ T cells in the blood and lungs, which was associated with the rapid recruitment of both innate and adaptive immune cells to lymph nodes draining the site of immunisation. mRNACV2 vaccination also provided significant pulmonary protection in M. tuberculosis-infected mice, reducing bacterial load and inflammatory infiltration in the lungs. Importantly, mRNACV2 enhanced immune responses and long-term protection when used to boost BCG-primed mice.

INTERPRETATION

These findings of a protective LNP-mRNA vaccine for TB highlight the potential of the LNP-mRNA platform for TB control and support further research to facilitate translation to humans.

FUNDING

This work was supported by the NHMRC Centre of Research Excellence in Tuberculosis Control to JAT and WJB (APP1153493), and MRFF mRNA Clinical Trial Enabling Infrastructure grant to CWP and HAW (MRFCTI000006).

Linking vaccine adjuvant mechanisms of action to function

Vaccines deliver an immunogen in a manner designed to safely provoke an immune response, leading to the generation of memory T and B cells and long-lived antibody-producing plasma cells. Adjuvants play a critical role in vaccines by controlling how the immune system is exposed to the immunogen and providing inflammatory cues that enable productive immune priming. However, mechanisms of action underlying adjuvant function at the molecular, cell, and tissue levels are diverse and often poorly understood. Here, we review the current understanding of mechanisms of action underlying adjuvants used in subunit protein/polysaccharide vaccines and mRNA vaccines, discuss where possible how these mechanisms of action link to downstream effects on the immune response, and identify knowledge gaps that will be important to fill in order to enable the continued development of more effective adjuvants for challenging pathogens such as HIV and emerging threats.

Variants and vaccines impact nasal immunity over three waves of SARS-CoV-2

Viral variant and host vaccination status impact infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), yet how these factors shift cellular responses in the human nasal mucosa remains uncharacterized. We performed single-cell RNA sequencing (scRNA-seq) on nasopharyngeal swabs from vaccinated and unvaccinated adults with acute Delta and Omicron SARS-CoV-2 infections and integrated with data from acute infections with ancestral SARS-CoV-2. Patients with Delta and Omicron exhibited greater similarity in nasal cell composition driven by myeloid, T cell and SARS-CoV-2hi cell subsets, which was distinct from that of ancestral cases. Delta-infected samples had a marked increase in viral RNA, and a subset of PER2+EGR1+GDF15+ epithelial cells was enriched in SARS-CoV-2 RNA+ cells in all variants. Prior vaccination was associated with increased frequency and activation of nasal macrophages. Expression of interferon-stimulated genes negatively correlated with coronavirus disease 2019 (COVID-19) severity in patients with ancestral and Delta but not Omicron variants. Our study defines nasal cell responses and signatures of disease severity across SARS-CoV-2 variants and vaccination.

Impact of SARS-CoV-2 vaccination and of seasonal variations on the innate immune inflammatory response

Introduction

The innate immune response is an important first checkpoint in the evolution of an infection. Although adaptive immunity is generally considered the immune component that retains antigenic memory, innate immune responses can also be affected by previous stimulations. This study evaluated the impact of vaccination on innate cell activation by TLR7/8 agonist R848, as well as seasonal variations.

Methods

To this end, blood samples from a cohort of 304 food and retail workers from the Quebec City region were collected during three visits at 12-week intervals. Peripheral blood mononuclear cells and polymorphonuclear neutrophils were isolated during the first and third visits and were stimulated with R848 to assess the innate immune response.

Results

Our results show that IL-8 production after stimulation decreased after vaccination. In addition, the IL-8 response was significantly different depending on the season when the visit occurred, for both COVID-19 vaccinated and unvaccinated individuals.

Discussion

This study highlights that innate immune responses can be affected by SARS-CoV-2 vaccination and fluctuate seasonally.

Outer membrane vesicles (OMVs) from Tenacibaculum maritimum as a potential vaccine against fish tenacibaculosis

Outer membrane vesicles (OMVs) have been gained increasing attention in vaccinology due to their ability to induce strong protective humoral and cell-mediated immunity. The Gram-negative bacterium Tenacibaculum maritimum, the causative agent of marine tenacibaculosis, poses a significant challenge to the global aquaculture industry due to its difficult prophylaxis. In previous studies, we demonstrated that OMV production is a key virulence mechanism in T. maritimum. Building on this, the present study aimed to evaluate the efficacy of a natural, encapsulated multi-antigen vaccine made from adjuvant-free, crude T. maritimum OMVs (Tm-OMVs). A vaccination experiment using SP9.1-OMVs was conducted in juvenile turbot (Scophthalmus maximus L.), followed by a T. maritimum bath challenge. Immune responses in the turbot were assessed by measuring anti-Tm antibody levels and analyzing the expression of eight key immune-related genes (il-1β, il-8, il-22, pcna, c3, cd4-1, ifng2, cd8α). The results showed that immunization with SP9.1-OMVs provided significant protection against T. maritimum infection (RPS = 70 %). Vaccinated fish exhibited a dose-dependent increase in anti-Tm antibody titers in blood plasma, along with rapid induction of both innate (il-1β, il-8, il-22, c3) and adaptive (cd4-1, ifng2, cd8α) immune genes as early as 4 h post-bath challenge. These findings offer new insights into the early immune response of turbot following T. maritimum infection and could serve as a foundation for developing novel OMV-based vaccines.

Elucidating allergic reaction mechanisms in response to SARS-CoV-2 mRNA vaccination in adults

BACKGROUND

During the COVID-19 pandemic, novel nanoparticle-based mRNA vaccines were developed. A small number of individuals developed allergic reactions to these vaccines although the mechanisms remain undefined.

METHODS

To understand COVID-19 vaccine-mediated allergic reactions, we enrolled 19 participants who developed allergic events within 2 h of vaccination and 13 controls, nonreactors. Using standard hemolysis assays, we demonstrated that sera from allergic participants induced stronger complement activation compared to nonallergic subjects following ex vivo vaccine exposure.

RESULTS

Vaccine-mediated complement activation correlated with anti-polyethelyne glycol (PEG) IgG (but not IgM) levels while anti-PEG IgE was undetectable in all subjects. Depletion of total IgG suppressed complement activation in select individuals. To investigate the effects of vaccine excipients on basophil function, we employed a validated indirect basophil activation test that stratified the allergic populations into high and low responders. Complement C3a and C5a receptor blockade in this system suppressed basophil response, providing strong evidence for complement involvement in vaccine-mediated basophil activation. Single-cell multiome analysis revealed differential expression of genes encoding the cytokine response and Toll-like receptor (TLR) pathways within the monocyte compartment. Differential chromatin accessibility for IL-13 and IL-1B genes was found in allergic and nonallergic participants, suggesting that in vivo, epigenetic modulation of mononuclear phagocyte immunophenotypes determines their subsequent functional responsiveness, contributing to the overall physiologic manifestation of vaccine reactions.

CONCLUSION

These findings provide insights into the mechanisms underlying allergic reactions to COVID-19 mRNA vaccines, which may be used for future vaccine strategies in individuals with prior history of allergies or reactions and reduce vaccine hesitancy.

Functional and epigenetic changes in monocytes from adults immunized with an AS01-adjuvanted vaccine

The adjuvant AS01 plays a key role in the immunogenicity of several approved human vaccines with demonstrated high efficacy. Its adjuvant effect relies on activation of the innate immune system. However, specific effects of AS01-adjuvanted vaccines on innate cell function and epigenetic remodeling, as described for Bacille Calmette-Guérin (BCG) and influenza vaccines, are still unknown. We assessed the long-term functional and epigenetic changes in circulating monocytes and dendritic cells induced by a model vaccine containing hepatitis B surface antigen and AS01 in healthy adults (NCT01777295). The AS01-adjuvanted vaccine, but not an Alum-adjuvanted vaccine, increased the number of circulating monocytes and their expression of human leukocyte antigen (HLA)-DR, which correlated with the magnitude of the memory CD4+ T cell response. Single-cell analyses revealed epigenetic alterations in monocyte and dendritic cell subsets, affecting accessibility of transcription factors involved in cell functions including activator protein-1 (AP-1), GATA, C/EBP, and interferon regulatory factor. The functional changes were characterized by a reduced proinflammatory response to Toll-like receptor activation and an improved response to interferon-γ, a cytokine critical for the adjuvant's mode of action. Epigenetic changes were most evident shortly after the second vaccine dose in CD14+ monocytes, for which accessibility differences of some transcription factors could persist for up to 6 months postvaccination. Together, we show that reprogramming of monocyte subsets occurs after vaccination with an AS01-adjuvanted vaccine, an effect that may contribute to the impact of vaccination beyond antigen-specific protection.

Evidence of innate training in bovine γδ T cells following subcutaneous BCG administration

The Bacillus Calmette Guerin (BCG) vaccine has been shown to induce non-specific protection against diseases other than tuberculosis in vaccinated individuals, attributed to the induction of trained immunity. We have previously demonstrated that BCG administration induces innate immune training in mixed peripheral blood mononuclear cells and monocytes in calves. Gamma Delta (γδ) T cells are non-conventional T cells that exhibit innate and adaptive immune system features. They are in higher proportion in the peripheral blood of cattle than humans or rodents and play an essential role in bovine immune response to pathogens. In the current study, we determined if BCG administration induced innate immune training in bovine γδ T cells. A group of 16 pre-weaned Holstein calves (2-4 d age) were enrolled in the study and randomly assigned to vaccine and control groups (n=8/group). The vaccine group received two doses of 106 colony forming units (CFU) BCG Danish strain subcutaneously, separated by 2 weeks. The control group remained unvaccinated. Gamma delta T cells were purified from peripheral blood using magnetic cell sorting three weeks after receiving the 1st BCG dose. We observed functional changes in the γδ T cells from BCG-treated calves shown by increased IL-6 and TNF-α cytokine production in response to in vitro stimulation with Escherichia coli LPS and PAM3CSK4. ATAC-Seq analysis of 78,278 regions of open chromatin (peaks) revealed that γδ T cells from BCG-treated calves had an altered epigenetic status compared to cells from the control calves. Differentially accessible peaks (DAP) found near the promoters of innate immunity-related genes like Siglec14, Irf4, Ifna2, Lrrfip1, and Tnfrsf10d were 1 to 4-fold more accessible in cells from BCG-treated calves. MOTIF enrichment analysis of the sequences within DAPs, which explores transcription factor binding motifs (TFBM) upstream of regulatory elements, revealed TFBM for Eomes and IRF-5 were among the most enriched transcription factors. GO enrichment analysis of genes proximal to the DAPs showed enrichment of pathways such as regulation of IL-2 production, T-cell receptor signaling pathway, and other immune regulatory pathways. In conclusion, our study shows that subcutaneous BCG administration in pre-weaned calves can induce innate immune memory in the form of trained immunity in γδ T cells. This memory is associated with increased chromatin accessibility of innate immune response-related genes, thereby inducing a functional trained immune response evidenced by increased IL-6 and TNF-α cytokine production.

Long-Lasting Enhanced Cytokine Responses Following SARS-CoV-2 BNT162b2 mRNA Vaccination

The mRNA vaccine against COVID-19 protects against severe disease by the induction of robust humoral and cellular responses. Recent studies have shown the capacity of some vaccines to induce enduring non-specific innate immune responses by the induction of trained immunity, augmenting protection against unrelated pathogens. This study aimed to assess whether the mRNA vaccine BNT162b2 can induce lasting non-specific immune responses in myeloid cells following a three-dose vaccination scheme. In a sample size consisting of 20 healthy individuals from Romania, we assessed inflammatory proteins using the Olink® Target 96 Inflammation panel, as well as ex vivo cytokine responses following stimulations with unrelated PRR ligands. We assessed the vaccine-induced non-specific systemic inflammation and functional adaptations of myeloid cells. Our results revealed the induction of a stimulus- and cytokine-dependent innate immune memory phenotype that became apparent after the booster dose and was maintained eight months later in the absence of systemic inflammation.

Cellular and humoral immune responses to COVID-19 booster vaccination in Japanese dialysis patients

BACKGROUND

Dialysis patients are susceptible to developing severe coronavirus disease 2019 (COVID-19) due to hypoimmunity. Antibody titers against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) after the primary vaccinations are lower in hemodialysis (HD) patients than in healthy individuals. This study aimed to evaluate the effect of a SARS-CoV-2 booster vaccination in HD and peritoneal dialysis (PD) patients based on antibody titers and cellular and humoral immunity.

METHODS

Participants of the control, HD, and PD groups were recruited from 12 facilities. SARS-CoV-2 antigen-specific cytokine and IgG-antibody levels were measured. Regulatory T cells and memory B cells were counted using flow cytometry at 6 months after primary vaccination with BNT162b2 and 3 weeks after the booster vaccination in HD and PD patients and compared with those of a control group.

RESULTS

Booster vaccination significantly enhanced the levels of antibodies, cytokines, and memory B cells in three groups. The HD group showed significantly higher levels of IgG-antibodies, IL-1β, IL-2, IL-4, IL-17, and memory B cells than those in the control group at 3 weeks after the booster dose. The PD group tended to show similar trends to HD patients but had similar levels of IgG-antibodies, cytokines, and memory B cells to the control group.

CONCLUSIONS

HD patients had significantly stronger cellular and humoral immune responses than the control 3 weeks after the booster dose. Our findings will help in developing better COVID-19 vaccination strategies for HD and PD patients.

Immune profiling of age and adjuvant-specific activation of human blood mononuclear cells in vitro

Vaccination reduces morbidity and mortality due to infections, but efficacy may be limited due to distinct immunogenicity at the extremes of age. This raises the possibility of employing adjuvants to enhance immunogenicity and protection. Early IFNγ production is a hallmark of effective vaccine immunogenicity in adults serving as a biomarker that may predict effective adjuvanticity. We utilized mass cytometry (CyTOF) to dissect the source of adjuvant-induced cytokine production in human blood mononuclear cells (BMCs) from newborns (~39-week-gestation), adults (~18-63 years old) and elders (>65 years of age) after stimulation with pattern recognition receptors agonist (PRRa) adjuvants. Dimensionality reduction analysis of CyTOF data mapped the BMC compartment, elucidated age-specific immune responses and profiled PRR-mediated activation of monocytes and DCs upon adjuvant stimulation. Furthermore, we demonstrated PRRa adjuvants mediated innate IFNγ induction and mapped NK cells as the key source of TLR7/8 agonist (TLR7/8a) specific innate IFNγ responses. Hierarchical clustering analysis revealed age and TLR7/8a-specific accumulation of innate IFNγ producing γδ T cells. Our study demonstrates the application of mass cytometry and cutting-edge computational approaches to characterize immune responses across immunologically distinct age groups and may inform identification of the bespoke adjuvantation systems tailored to enhance immunity in distinct vulnerable populations.

Modulation of innate immune response to mRNA vaccination after SARS-CoV-2 infection or sequential vaccination in humans

mRNA vaccines are likely to become widely used for the prevention of infectious diseases in the future. Nevertheless, a notable gap exists in mechanistic data, particularly concerning the potential effects of sequential mRNA immunization or preexisting immunity on the early innate immune response triggered by vaccination. In this study, healthy adults, with or without documented prior SARS-CoV-2 infection, were vaccinated with the BNT162b2/Comirnaty mRNA vaccine. Prior infection conferred significantly stronger induction of proinflammatory and type I IFN-related gene signatures, serum cytokines, and monocyte expansion after the prime vaccination. The response to the second vaccination further increased the magnitude of the early innate response in both study groups. The third vaccination did not further increase vaccine-induced inflammation. In vitro stimulation of PBMCs with TLR ligands showed no difference in cytokine responses between groups, or before or after prime vaccination, indicating absence of a trained immunity effect. We observed that levels of preexisting antigen-specific CD4 T cells, antibody, and memory B cells correlated with elements of the early innate response to the first vaccination. Our data thereby indicate that preexisting memory formed by infection may augment the innate immune activation induced by mRNA vaccines.

Characteristics of emerging new autoimmune diseases after COVID-19 vaccination: A sub-study by the COVAD group

BACKGROUND

Despite the overall safety and efficacy of COVID-19 vaccinations, rare cases of systemic autoimmune diseases (SAIDs) have been reported post-vaccination. This study used a global survey to analyze SAIDs in susceptible individuals' post-vaccination.

METHODS

A cross-sectional study was conducted among participants with self-reported new-onset SAIDs using the COVID-19 Vaccination in Autoimmune Diseases (COVAD) 2 study dataset-a validated, patient-reported e-survey-to analyze the long-term safety of COVID-19 vaccines. Baseline characteristics of patients with new-onset SAIDs and vaccinated healthy controls (HCs) were compared after propensity score matching based on age and sex in a 1:4 ratio.

RESULTS

Of 16 750 individuals, 74 (median age 52 years, 79.9% females, and 76.7% Caucasians) had new-onset SAID post-vaccination, mainly idiopathic inflammatory myopathies (IIMs) (n = 23, 31.51%), arthritis (n = 15; 20.53%), and polymyalgia rheumatica (PMR) (n = 12, 16.40%). Higher odds of new-onset SAIDs were noted among Caucasians (OR = 5.3; 95% CI = 2.9-9.7; p < .001) and Moderna vaccine recipients (OR = 2.7; 95% CI = 1.3-5.3; p = .004). New-onset SAIDs were associated with AID multimorbidity (OR = 1.4; 95% CI = 1.1-1.7; p < .001), mental health disorders (OR = 1.6; 95% CI = 1.3-1.9; p < .001), and mixed race (OR = 2.2; 95% CI = 1.2-4.2; p = .010), where those aged >60 years (OR = 0.6; 95% CI = 0.4-0.8; p = .007) and from high/medium human development index (HDI) countries (compared to very high HDI) reported fewer events than HCs.

CONCLUSION

This study reports a low occurrence of new-onset SAIDs following COVID-19 vaccination, primarily IIMs, PMR, and inflammatory arthritis. Identified risk factors included pre-existing AID multimorbidity, mental health diseases, and mixed race. Revaccination was well tolerated by most patients; therefore, we recommend continuing COVID-19 vaccination in the general population. However, long-term studies are needed to understand the autoimmune phenomena arising post-vaccination.

Specific and off-target immune responses following COVID-19 vaccination with ChAdOx1-S and BNT162b2 vaccines-an exploratory sub-study of the BRACE trial

BACKGROUND

The COVID-19 pandemic led to the rapid development and deployment of several highly effective vaccines against SARS-CoV-2. Recent studies suggest that these vaccines may also have off-target effects on the immune system. We sought to determine and compare the off-target effects of the adenovirus vector ChAdOx1-S (Oxford-AstraZeneca) and modified mRNA BNT162b2 (Pfizer-BioNTech) vaccines on immune responses to unrelated pathogens.

METHODS

Prospective sub-study within the BRACE trial. Blood samples were collected from 284 healthcare workers before and 28 days after ChAdOx1-S or BNT162b2 vaccination. SARS-CoV-2-specific antibodies were measured using ELISA, and whole blood cytokine responses to specific (SARS-CoV-2) and unrelated pathogen stimulation were measured by multiplex bead array.

FINDINGS

Both vaccines induced robust SARS-CoV-2 specific antibody and cytokine responses. ChAdOx1-S vaccination increased cytokine responses to heat-killed (HK) Candida albicans and HK Staphylococcus aureus and decreased cytokine responses to HK Escherichia coli and BCG. BNT162b2 vaccination decreased cytokine response to HK E. coli and had variable effects on cytokine responses to BCG and resiquimod (R848). After the second vaccine dose, BNT162b2 recipients had greater specific and off-target cytokine responses than ChAdOx1-S recipients.

INTERPRETATION

ChAdOx1-S and BNT162b2 vaccines alter cytokine responses to unrelated pathogens, indicative of potential off-target effects. The specific and off-target effects of these vaccines differ in their magnitude and breadth. The clinical relevance of these findings is uncertain and needs further study.

FUNDING

Bill & Melinda Gates Foundation, National Health and Medical Research Council, Swiss National Science Foundation and the Melbourne Children's. BRACE trial funding is detailed in acknowledgements.

Impaired innate and adaptive immune responses to BNT162b2 SARS-CoV-2 vaccination in systemic lupus erythematosus

Understanding the immune responses to SARS-CoV-2 vaccination is critical to optimizing vaccination strategies for individuals with autoimmune diseases, such as systemic lupus erythematosus (SLE). Here, we comprehensively analyzed innate and adaptive immune responses in 19 patients with SLE receiving a complete 2-dose Pfizer-BioNTech mRNA vaccine (BNT162b2) regimen compared with a control cohort of 56 healthy control (HC) volunteers. Patients with SLE exhibited impaired neutralizing antibody production and antigen-specific CD4+ and CD8+ T cell responses relative to HC. Interestingly, antibody responses were only altered in patients with SLE treated with immunosuppressive therapies, whereas impairment of antigen-specific CD4+ and CD8+ T cell numbers was independent of medication. Patients with SLE also displayed reduced levels of circulating CXC motif chemokine ligands, CXCL9, CXCL10, CXCL11, and IFN-γ after secondary vaccination as well as downregulation of gene expression pathways indicative of compromised innate immune responses. Single-cell RNA-Seq analysis reveals that patients with SLE showed reduced levels of a vaccine-inducible monocyte population characterized by overexpression of IFN-response transcription factors. Thus, although 2 doses of BNT162b2 induced relatively robust immune responses in patients with SLE, our data demonstrate impairment of both innate and adaptive immune responses relative to HC, highlighting a need for population-specific vaccination studies.

Biodistribution of RNA Vaccines and of Their Products: Evidence from Human and Animal Studies

Explosive developments in mRNA vaccine technology in the last decade have made it possible to achieve great success in clinical trials of mRNA vaccines to prevent infectious diseases and develop cancer treatments and mRNA-based gene therapy products. The approval of the mRNA-1273 and BNT162b2 mRNA vaccines against SARS-CoV-2 by the U.S. Food and Drug Administration has led to mass vaccination (with mRNA vaccines) of several hundred million people around the world, including children. Despite its effectiveness in the fight against COVID-19, rare adverse effects of the vaccination have been shown in some studies, including vascular microcirculation disorders and autoimmune and allergic reactions. The biodistribution of mRNA vaccines remains one of the most poorly investigated topics. This mini-review discussed the results of recent experimental studies on humans and rodents regarding the biodistribution of mRNA vaccines, their constituents (mRNA and lipid nanoparticles), and their encoded antigens. We focused on the dynamics of the biodistribution of mRNA vaccine products and on the possibility of crossing the blood-brain and blood-placental barriers as well as transmission to infants through breast milk. In addition, we critically assessed the strengths and weaknesses of the detection methods that have been applied in these articles, whose results' reliability is becoming a subject of debate.

Interaction dynamics between innate and adaptive immune cells responding to SARS-CoV-2 vaccination in non-human primates

As SARS-CoV-2 variants continue evolving, testing updated vaccines in non-human primates remains important for guiding human clinical practice. To date, such studies have focused on antibody titers and antigen-specific B and T cell frequencies. Here, we extend our understanding by integrating innate and adaptive immune responses to mRNA-1273 vaccination in rhesus macaques. We sorted innate immune cells from a pre-vaccine time point, as well as innate immune cells and antigen-specific peripheral B and T cells two weeks after each of two vaccine doses and used single-cell sequencing to assess the transcriptomes and adaptive immune receptors of each cell. We show that a subset of S-specific T cells expresses cytokines critical for activating innate responses, with a concomitant increase in CCR5-expressing intermediate monocytes and a shift of natural killer cells to a more cytotoxic phenotype. The second vaccine dose, administered 4 weeks after the first, elicits an increase in circulating germinal center-like B cells 2 weeks later, which are more clonally expanded and enriched for epitopes in the receptor binding domain. Both doses stimulate inflammatory response genes associated with elevated antibody production. Overall, we provide a comprehensive picture of bidirectional signaling between innate and adaptive components of the immune system and suggest potential mechanisms for the enhanced response to secondary exposure.

Trained immunity: Target for prophylaxis and therapy

Trained immunity is a de facto memory for innate immune responses, leading to long-term functional reprogramming of innate immune cells. In physiological conditions, trained immunity leads to adaptive states that enhance resistance against pathogens and contributes to immunosurveillance. Dysregulated trained immunity can however lead either to defective innate immune responses in severe infections or cancer or to inflammatory and autoimmune diseases if trained immunity is inappropriately activated. Here, we review the immunological and molecular mechanisms that mediate trained immunity induction and propose that trained immunity represents an important target for prophylactic and therapeutic approaches in human diseases. On the one hand, we argue that novel approaches that induce trained immunity may enhance vaccine efficacy. On the other hand, induction of trained immunity in cancer, and inhibition of exaggerated induction of trained immunity in inflammatory disorders, are viable targets amenable for new therapeutic approaches.

The impact of BNT162b2 mRNA vaccine on adaptive and innate immune responses

The mRNA-based BNT162b2 protects against severe disease and mortality caused by SARS-CoV-2 via induction of specific antibody and T-cell responses. Much less is known about its broad effects on immune responses against other pathogens. Here, we investigated the adaptive immune responses induced by BNT162b2 vaccination against various SARS-CoV-2 variants and its effects on the responsiveness of immune cells upon stimulation with heterologous stimuli. BNT162b2 vaccination induced effective humoral and cellular immunity against SARS-CoV-2 that started to wane after six months. We also observed long-term transcriptional changes in immune cells after vaccination. Additionally, vaccination with BNT162b2 modulated innate immune responses as measured by inflammatory cytokine production after stimulation - higher IL-1/IL-6 release and decreased IFN-α production. Altogether, these data expand our knowledge regarding the overall immunological effects of this new class of vaccines and underline the need for additional studies to elucidate their effects on both innate and adaptive immune responses.

Memory-like innate response to booster vaccination with MF-59 adjuvanted influenza vaccine in children

The pediatric population receives the majority of vaccines globally, yet there is a paucity of studies on the transcriptional response induced by immunization in this special population. In this study, we performed a systems-level analysis of immune responses to the trivalent inactivated influenza vaccine adjuvanted with MF-59 in children (15-24 months old) and in young, healthy adults. We analyzed transcriptional responses elicited by vaccination in peripheral blood, as well as cellular and antibody responses following primary and booster vaccinations. Our analysis revealed that primary vaccination induced a persistent transcriptional signature of innate immunity; booster vaccination induced a transcriptional signature of an enhanced memory-like innate response, which was consistent with enhanced activation of myeloid cells assessed by flow cytometry. Furthermore, we identified a transcriptional signature of type 1 interferon response post-booster vaccination and at baseline that was correlated with the local reactogenicity to vaccination and defined an early signature that correlated with the hemagglutinin antibody titers. These results highlight an adaptive behavior of the innate immune system in evoking a memory-like response to secondary vaccination and define molecular correlates of reactogenicity and immunogenicity in infants.

Cellular and Humoral Immune Responses after Breakthrough Infection in Patients Undergoing Hemodialysis

Coronavirus disease 2019 (COVID-19) following primary immunization (breakthrough infection) has been reported in hemodialysis patients; however, their post-infection immune status remains unclear. We evaluated the humoral and cellular immunity of hemodialysis patients after breakthrough infection. Hemodialysis patients who had received primary immunization against COVID-19 at least six months prior to the study but developed mild/moderate COVID-19 before a booster dose (breakthrough infection group) and hemodialysis patients who were not infected with COVID-19 but received a booster dose (booster immunization group) were recruited. In both groups, SARS-CoV-2 antigen-specific cytokines and IgG levels were measured three weeks after infection or three weeks after receiving a booster dose. Memory T and B cells were also counted in the breakthrough infection group using flow cytometry three weeks after infection. Significantly higher SARS-CoV-2 antigen-specific IgG, IFN-γ, IL-5, TNF-α, and IL-6 levels occurred in the breakthrough infection group compared to the booster immunization group (p = 0.013, 0.039, 0.024, 0.017, and 0.039, respectively). The SARS-CoV-2 antigen-specific IgG and cytokine levels were not significantly different between the two groups. The breakthrough infection group had significantly higher percentages of central and effector memory T cells and regulatory T cells than the comparison group (p = 0.008, 0.031, and 0.026, respectively). Breakthrough infections may induce stronger cellular and humoral immune responses than booster immunizations in hemodialysis patients.

In-depth characterization of long-term humoral and cellular immune responses to COVID-19m-RNA vaccination in multiple sclerosis patients treated with teriflunomide or alemtuzumab

BACKGROUND

The impact of disease-modifying therapies on the efficacy to mount appropriate immune responses to COVID-19 vaccination in patients with multiple sclerosis (MS) is currently under investigation.

OBJECTIVE

To characterize long-term humoral and cellular immunity in mRNA-COVID-19 MS vaccinees treated with teriflunomide or alemtuzumab.

METHODS

We prospectively measured SARS-COV-2 IgG, memory B-cells specific for SARS-CoV-2 RBD, and memory T-cells secreting IFN-γ and/or IL-2, in MS patients vaccinated with BNT162b2-COVID-19 vaccine before, 1, 3 and 6 months after the second vaccine dose, and 3-6 months following vaccine booster.

RESULTS

Patients were either untreated (N = 31, 21 females), under treatment with teriflunomide (N = 30, 23 females, median treatment duration 3.7 years, range 1.5-7.0 years), or under treatment with alemtuzumab (N = 12, 9 females, median time from last dosing 15.9 months, range 1.8-28.7 months). None of the patients had clinical SARS-CoV-2 or immune evidence for prior infection. Spike IgG titers were similar between untreated, teriflunomide and alemtuzumab treated MS patients both at 1 month (median 1320.7, 25-75 IQR 850.9-3152.8 vs. median 901.7, 25-75 IQR 618.5-1495.8, vs. median 1291.9, 25-75 IQR 590.8-2950.9, BAU/ml, respectively), at 3 months (median 1388.8, 25-75 1064.6-2347.6 vs. median 1164.3 25-75 IQR 726.4-1399.6, vs. median 837.2, 25-75 IQR 739.4-1868.5 BAU/ml, respectively), and at 6 months (median 437.0, 25-75 206.1-1161.3 vs. median 494.3, 25-75 IQR 214.6-716.5, vs. median 176.3, 25-75 IQR 72.3-328.8 BAU/ml, respectively) after the second vaccine dose. Specific SARS-CoV-2 memory B cells were detected in 41.9%, 40.0% and 41.7% of subjects at 1 month, in 32.3%, 43.3% and 25% at 3 months, and in 32.3%, 40.0%, 33.3% at 6 months following vaccination in untreated, teriflunomide treated and alemtuzumab treated MS patients, respectively. Specific SARS-CoV-2 memory T cells were found in 48.4%, 46.7% and 41.7 at 1 month, in 41.9%, 56.7% and 41.7% at 3 months, and in 38.7%, 50.0%, and 41.7% at 6 months, of untreated, teriflunomide-treated and alemtuzumab -treated MS patients, respectively. Administration of a third vaccine booster significantly increased both humoral and cellular responses in all patients.

CONCLUSIONS

MS patients treated with teriflunomide or alemtuzumab achieved effective humoral and cellular immune responses up to 6 months following second COVID-19 vaccination. Immune responses were reinforced following the third vaccine booster.

Importance, Applications and Features of Assays Measuring SARS-CoV-2 Neutralizing Antibodies

More than three years ago, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) caused the unforeseen COVID-19 pandemic with millions of deaths. In the meantime, SARS-CoV-2 has become endemic and is now part of the repertoire of viruses causing seasonal severe respiratory infections. Due to several factors, among them the development of SARS-CoV-2 immunity through natural infection, vaccination and the current dominance of seemingly less pathogenic strains belonging to the omicron lineage, the COVID-19 situation has stabilized. However, several challenges remain and the possible new occurrence of highly pathogenic variants remains a threat. Here we review the development, features and importance of assays measuring SARS-CoV-2 neutralizing antibodies (NAbs). In particular we focus on in vitro infection assays and molecular interaction assays studying the binding of the receptor binding domain (RBD) with its cognate cellular receptor ACE2. These assays, but not the measurement of SARS-CoV-2-specific antibodies per se, can inform us of whether antibodies produced by convalescent or vaccinated subjects may protect against the infection and thus have the potential to predict the risk of becoming newly infected. This information is extremely important given the fact that a considerable number of subjects, in particular vulnerable persons, respond poorly to the vaccination with the production of neutralizing antibodies. Furthermore, these assays allow to determine and evaluate the virus-neutralizing capacity of antibodies induced by vaccines and administration of plasma-, immunoglobulin preparations, monoclonal antibodies, ACE2 variants or synthetic compounds to be used for therapy of COVID-19 and assist in the preclinical evaluation of vaccines. Both types of assays can be relatively quickly adapted to newly emerging virus variants to inform us about the magnitude of cross-neutralization, which may even allow us to estimate the risk of becoming infected by newly appearing virus variants. Given the paramount importance of the infection and interaction assays we discuss their specific features, possible advantages and disadvantages, technical aspects and not yet fully resolved issues, such as cut-off levels predicting the degree of in vivo protection.

Efficacy and risk of mRNA vaccination in patients with autoimmune inflammatory rheumatic diseases

Coronavirus disease 2019 (COVID-19), which spread worldwide from Wuhan, China, in 2019, appeared for a time to be overcome by the remarkable efficacy of mRNA vaccines; however, new variants of severe acute respiratory syndrome coronavirus 2 have emerged and remain rampant. The involvement of the virus in the emergence of variant strains and the relationship between vaccine efficacy and immunosuppressive drugs have attracted significant attention, particularly with regard to patients with autoimmune inflammatory rheumatic disease (AIRD) who take immunosuppressive drugs. This review outlines the relationship between mRNA vaccines, one of the key strategies against COVID-19, and AIRD and discusses the immune response elicited by mRNA vaccines. Furthermore, the impact of immunosuppressive agents on the mRNA vaccine-induced immune response in patients with AIRD and side effects of the vaccine, such as exacerbation of the underlying disease, is outlined.

Protection from COVID-19 disease in hamsters vaccinated with subunit SARS-CoV-2 S1 mucosal vaccines adjuvanted with different adjuvants

Introduction

Adjuvant plays an important role in directing the immune responses induced by vaccines. In previous studies, we have shown that a mucosal SARS-CoV-2 S1 subunit vaccine adjuvanted with a combination of CpG, Poly I:C and IL-15 (named CP15) induced effective mucosal and systemic immunity and conferred nearly sterile protection against SARS-CoV-2 viral replication in macaque models.

Methods

In this study, we used a hamster model, which mimics the human scenario and reliably exhibits severe SARS-CoV-2 disease similar to hospitalized patients, to investigate the protection efficacy of the vaccines against COVID-19 disease. We compared the weight loss, viral loads (VLs), and clinical observation scores of three different vaccine regimens. All three regimens consisted of priming/boosting with S1 subunit vaccines, but adjuvanted with alum and/or CP15 administrated by either intramuscular (IM) or intranasal (IN) routes: Group 1 was adjuvanted with alum/alum administrated IM/IM; Group 2 was alum-IM/CP15-IN; and Group 3 was CP15-IM/CP15-IN.

Results

After challenge with SARS-CoV-2 WA strain, we found that the alum/CP15 group showed best protection against weight loss, while the CP15 group demonstrated best reduction of oral SARS-CoV-2 VLs, suggesting that the protection profiles were different. Sex differences for VL and clinical scores were observed. Humoral immunity was induced but not correlated with protection. Moreover, S1-specific binding antibody titers against beta, omicron BA.1, and BA.2 variants showed 2.6-, 4.9- and 2.8- fold reduction, respectively, compared to the Wuhan strain.

Discussion

Overall, the data suggested that adjuvants in subunit vaccines determine the protection profiles after SARS-CoV-2 infection and that nasal/oral mucosal immunization can protect against systemic COVID-19 disease.