Antibody-mediated NK cell activation as a correlate of immunity against influenza infection

The mouse monoclonal antibody 4E3 is specific for the G1m17 allotype of human IgG1

Allotype is an amino acid variation within the immunoglobulin isotypes. Four allotypes have been described for human IgG1 and two of them (G1m3 and G1m17) are located at position 214 in the CH1 region of the gamma chain. Various diseases have been associated with allotype expression, making the allotype research an interesting field in immunology. However, allotype-specific reagents are rare. In the present study the specificity of a widely used and commercially available IgG1-specific monoclonal antibody named 4E3, described as binding to the hinge region of IgG1, was evaluated. Using the ImmunoCAP™ assay technology, surprisingly no IgG1 was measured in 13 of 23 human serum and plasma samples when 4E3 was used in an antibody-enzyme conjugate as detection reagent. Further evaluation of 4E3 using eight IgG1 myeloma paraproteins revealed that 4E3 did not bind to three of them. No association was seen between the binding pattern and myeloma light chain glycosylation or the kappa or light chain use. By comparing the myeloma paraprotein binding patterns of 4E3 and TM14 (a monoclonal antibody with known G1m3 specificity), it was indicated that 4E3 only bound to myeloma paraproteins expressing the G1m17 allotype. This was confirmed using recombinant human antibodies expressing either the G1m3 or G1m17 allotype. The G1m17 bias of 4E3 seen using ImmunoCAP was also observed in microtiter plate-based enzyme-linked immunosorbent assays. The antibody 4E3 has a G1m17 bias limiting its use in assays to measure IgG1 antibodies. However, it may be a valuable allotype-specific reagent.

Transforming vaccinology

The COVID-19 pandemic placed the field of vaccinology squarely at the center of global consciousness, emphasizing the vital role of vaccines as transformative public health tools. The impact of vaccines was recently acknowledged by the award of the 2023 Nobel Prize in Physiology or Medicine to Katalin Kariko and Drew Weissman for their seminal contributions to the development of mRNA vaccines. Here, we provide a historic perspective on the key innovations that led to the development of some 27 licensed vaccines over the past two centuries and recent advances that promise to transform vaccines in the future. Technological revolutions such as reverse vaccinology, synthetic biology, and structure-based design transformed decades of vaccine failures into successful vaccines against meningococcus B and respiratory syncytial virus (RSV). Likewise, the speed and flexibility of mRNA vaccines profoundly altered vaccine development, and the advancement of novel adjuvants promises to revolutionize our ability to tune immunity. Here, we highlight exciting new advances in the field of systems immunology that are transforming our mechanistic understanding of the human immune response to vaccines and how to predict and manipulate them. Additionally, we discuss major immunological challenges such as learning how to stimulate durable protective immune response in humans.

An innate immune signature induced by AS01- or AS03-adjuvanted vaccines predicts the antibody response magnitude and quality consistently over time

Background

Antibody-mediated protection can depend on mechanisms varying from neutralization to Fc-dependent innate immune-cell recruitment. Adjuvanted vaccine development relies on a holistic understanding of how adjuvants modulate the quantity/titer and quality of the antibody response.

Methods

A Phase 2 trial (ClinicalTrials.gov: NCT00805389) evaluated hepatitis B vaccines formulated with licensed adjuvants (AS01B, AS01E, AS03, AS04 or Alum) in antigen-naïve adults. The trial investigated the role of adjuvants in shaping antibody-effector functions, and identified an innate transcriptional response shared by AS01B, AS01E and AS03. We integrated previously reported data on the innate response (gene expression, cytokine/C-reactive protein levels) and on quantitative/qualitative features of the mature antibody response (Fc-related parameters, immunoglobulin titers, avidity). Associations between the innate and humoral parameters were explored using systems vaccinology and a machine-learning framework.

Results

A dichotomy in responses between AS01/AS03 and AS04/Alum (with the former two contributing most to the association with the humoral response) was observed across all timepoints of this longitudinal study. The consistent patterns over time suggested a similarity in the impacts of the two-dose immunization regimen, year-long interval, and non-adjuvanted antigenic challenge given one year later. An innate signature characterized by interferon pathway-related gene expression and secreted interferon-γ-induced protein 10 and C-reactive protein, which was shared by AS01 and AS03, consistently predicted both the qualitative antibody response features and the titers. The signature also predicted from the antibody response quality, the group of adjuvants from which the administered vaccine was derived.

Conclusion

An innate signature induced by AS01- or AS03-adjuvanted vaccines predicts the antibody response magnitude and quality consistently over time.

Anti-TNF therapy impairs both short- and long-term IgG responses after repeated vaccination

BACKGROUND

Recently, it has been questioned whether vaccination of patients with inflammatory (auto)immune diseases under anti-tumor necrosis factor (TNF) treatment leads to impaired vaccine-induced immune responses and protection against breakthrough infections. However, the effects of TNF blockade on short- and long-term immune responses after repeated vaccination remain unclear. Vaccination studies have shown that initial short-term IgG antibodies (Abs) carry highly galactosylated and sialylated Fc glycans, whilst long-term IgG Abs have low levels of galactosylation and sialylation and are most likely generated by long-lived plasma cells (PCs) derived primarily from the germinal center (GC) response. Thus, IgG Fc glycosylation patterns may be applicable to distinguish short- and long-term vaccine responses after repeated vaccination under the influence of anti-TNF treatment.

METHODS

We used COVID-19 vaccination as a model to investigate vaccine-induced IgG subclass levels and Fc glycosylation patterns, B cell subsets, and effector functions of short- and long-term Ab responses after up to three vaccinations in patients on anti-TNF or other immunosuppressive treatments and in healthy individuals. Using TriNetX, a global healthcare database, we determined the risk of SARS-CoV-2 breakthrough infections in vaccinated patients treated with anti-TNF or other immunosuppressive drugs.

RESULTS

Anti-TNF treatment reduced the long-term abundance of all anti-S IgG subclasses with low levels of galactosylation and sialylation. Re-activation of potential memory B cells initially generated highly galactosylated and sialylated IgG antibodies, which were progressively reduced after each booster dose in anti-TNF-treated patients, especially in the elderly. The reduced short- and long-term IgG (1) levels in anti-TNF-treated patients correlated with diminished functional activity and an increased risk for the development of COVID-19.

CONCLUSIONS

The data suggest that anti-TNF treatment reduces both GC-dependent long-lived PCs and GC-dependent memory B cell-derived short-lived PCs, hence both the long- and short-term IgG subclass responses, respectively, after repeated vaccination. We propose that anti-TNF therapy, especially in the elderly, reduces the benefit of booster vaccination.

Murine modeling of menstruation identifies immune correlates of protection during Chlamydia muridarum challenge

The menstrual cycle influences the risk of acquiring sexually transmitted infections (STIs), including Chlamydia trachomatis (C. trachomatis), although the underlying immune contributions are poorly defined. A mouse model simulating the immune-mediated process of menstruation could provide valuable insights into tissue-specific determinants of protection against chlamydial infection within the cervicovaginal and uterine mucosae comprising the female reproductive tract (FRT). Here, we used the pseudopregnancy approach in naïve C57Bl/6 mice and performed vaginal challenge with Chlamydia muridarum (C. muridarum) at decidualization, endometrial tissue remodeling, or uterine repair. This strategy identified that the time frame comprising uterine repair correlated with robust infection and greater bacterial burden as compared with mice on hormonal contraception, while challenges during endometrial remodeling were least likely to result in a productive infection. By comparing the infection site at early time points following chlamydial challenge, we found that a greater abundance of innate effector populations and proinflammatory signaling, including IFNγ correlated with protection. FRT immune profiling in uninfected mice over pseudopregnancy or in pig-tailed macaques over the menstrual cycle identified NK cell infiltration into the cervicovaginal tissues and lumen over the course of endometrial remodeling. Notably, NK cell depletion over this time frame reversed protection, with mice now productively infected with C. muridarum following challenge. This study shows that the pseudopregnancy murine menstruation model recapitulates immune changes in the FRT as a result of endometrial remodeling and identifies NK cell localization at the FRT as essential for immune protection against primary C. muridarum infection.

Diverging patterns in innate immunity against respiratory viruses during a lifetime: lessons from the young and the old

Respiratory viral infections frequently lead to severe respiratory disease, particularly in vulnerable populations such as young children, individuals with chronic lung conditions and older adults, resulting in hospitalisation and, in some cases, fatalities. The innate immune system plays a crucial role in monitoring for, and initiating responses to, viruses, maintaining a state of preparedness through the constant expression of antimicrobial defence molecules. Throughout the course of infection, innate immunity remains actively involved, contributing to viral clearance and damage control, with pivotal contributions from airway epithelial cells and resident and newly recruited immune cells. In instances where viral infections persist or are not effectively eliminated, innate immune components prominently contribute to the resulting pathophysiological consequences. Even though both young children and older adults are susceptible to severe respiratory disease caused by various respiratory viruses, the underlying mechanisms may differ significantly. Children face the challenge of developing and maturing their immunity, while older adults contend with issues such as immune senescence and inflammaging. This review aims to compare the innate immune responses in respiratory viral infections across both age groups, identifying common central hubs that could serve as promising targets for innovative therapeutic and preventive strategies, despite the apparent differences in underlying mechanisms.

Immunoglobulin G genetic variation can confound assessment of antibody levels via altered binding to detection reagents

Objectives

Amino acid variations across more than 30 immunoglobulin (Ig) allotypes may introduce structural changes that influence recognition by anti-Ig detection reagents, consequently confounding interpretation of antibody responses, particularly in genetically diverse cohorts. Here, we assessed a panel of commercial monoclonal anti-IgG1 clones for capacity to universally recognise two dominant IgG1 haplotypes (G1m-1,3 and G1m1,17).

Methods

Four commercial monoclonal anti-human IgG1 clones were assessed via ELISAs and multiplex bead-based assays for their ability to bind G1m-1,3 and G1m1,17 IgG1 variants. Detection antibodies were validated against monoclonal IgG1 allotype standards and tested for capacity to recognise antigen-specific plasma IgG1 from G1m-1,3 and G1m1,17 homozygous and heterozygous SARS-CoV-2 BNT162b2 vaccinated (n = 28) and COVID-19 convalescent (n = 44) individuals. An Fc-specific pan-IgG detection antibody corroborated differences between hinge- and Fc-specific anti-IgG1 responses.

Results

Hinge-specific anti-IgG1 clone 4E3 preferentially bound G1m1,17 compared to G1m-1,3 IgG1. Consequently, SARS-CoV-2 Spike-specific IgG1 levels detected in G1m1,17/G1m1,17 BNT162b2 vaccinees appeared 9- to 17-fold higher than in G1m-1,3/G1m-1,3 vaccinees. Fc-specific IgG1 and pan-IgG detection antibodies equivalently bound G1m-1,3 and G1m1,17 IgG1 variants, and detected comparable Spike-specific IgG1 levels between haplotypes. IgG1 responses against other human coronaviruses and influenza were similarly poorly detected by 4E3 anti-IgG1 in G1m-1,3/G1m-1,3 subjects.

Conclusion

Anti-IgG1 clone 4E3 confounds assessment of antibody responses in clinical cohorts owing to bias towards detection of G1m1,17 IgG1 variants. Validation of anti-Ig clones should include evaluation of binding to relevant antibody variants, particularly as the role of immunogenetics upon humoral immunity is increasingly explored in diverse populations.

Cytokine-responsive T- and NK-cells portray SARS-CoV-2 vaccine-responders and infection in multiple myeloma patients

Patients with multiple myeloma (MM) routinely receive mRNA-based vaccines to reduce COVID-19-related mortality. However, whether disease- and therapy-related alterations in immune cells and cytokine-responsiveness contribute to the observed heterogeneous vaccination responses is unclear. Thus, we analyzed peripheral blood mononuclear cells from patients with MM during and after SARS-CoV-2 vaccination and breakthrough infection (BTI) using combined whole-transcriptome and surface proteome single-cell profiling with functional serological and T-cell validation in 58 MM patients. Our results demonstrate that vaccine-responders showed a significant overrepresentation of cytotoxic CD4+ T- and mature CD38+ NK-cells expressing FAS+/TIM3+ with a robust cytokine-responsiveness, such as type-I-interferon-, IL-12- and TNF-α-mediated signaling. Patients with MM experiencing BTI developed strong serological and cellular responses and exhibited similar cytokine-responsive immune cell patterns as vaccine-responders. This study can expand our understanding of molecular and cellular patterns associated with immunization responses and may benefit the design of improved vaccination strategies in immunocompromised patients.