Suppressed IgG4 class switching in dupilumab- and TNF inhibitor-treated patients after mRNA vaccination

BACKGROUND

The noninflammatory immunoglobulin G4 (IgG4) is linked to tolerance and is unique to humans. Although poorly understood, prolonged antigenic stimulation and IL-4-signaling along the T helper 2-axis may be instrumental in IgG4 class switching. Recently, repeated SARS-CoV-2 mRNA vaccination has been linked to IgG4 skewing. Although widely used immunosuppressive drugs have been shown to only moderately affect humoral responses to SARS-CoV-2 mRNA vaccination, the effect on IgG4 switching has not been investigated.

METHODS

Here we study the impact of such immunosuppressive drugs, including the IL-4 receptor-blocking antibody dupilumab, on IgG4 skewing upon repeated SARS-CoV-2 mRNA vaccination. Receptor-binding domain (RBD) specific antibody responses were longitudinally measured in 600 individuals, including patients with immune-mediated inflammatory diseases treated with a TNF inhibitor (TNFi) and/or methotrexate (MTX), dupilumab, and healthy/untreated controls, after repeated mRNA vaccination.

RESULTS

We observed a substantial increase in the proportion of RBD-specific IgG4 antibodies (median 21%) in healthy/untreated controls after third vaccination. This IgG4 skewing was profoundly reduced in dupilumab-treated patients (<1%). Unexpectedly, an equally strong suppression of IgG4 skewing was observed in TNFi-treated patients (<1%), whereas MTX caused a modest reduction (7%). RBD-specific total IgG levels were hardly affected by these immunosuppressive drugs. Minimal skewing was observed, when primary vaccination was adenoviral vector-based.

CONCLUSIONS

Our results imply a critical role for IL-4/IL-13 as well as TNF in vivo IgG4 class switching. These novel findings advance our understanding of IgG4 class switch dynamics, and may benefit humoral tolerance induction strategies, treatment of IgG4 pathologies and mRNA vaccine optimization.

The unique properties of IgG4 and its roles in health and disease

IgG4 is the least abundant subclass of IgG in human serum and has unique functional features. IgG4 is largely unable to activate antibody-dependent immune effector responses and, furthermore, undergoes Fab (fragment antigen binding)-arm exchange, rendering it bispecific for antigen binding and functionally monovalent. These properties of IgG4 have a blocking effect, either on the immune response or on the target protein of IgG4. In this Review, we discuss the unique structural characteristics of IgG4 and how these contribute to its roles in health and disease. We highlight how, depending on the setting, IgG4 responses can be beneficial (for example, in responses to allergens or parasites) or detrimental (for example, in autoimmune diseases, in antitumour responses and in anti-biologic responses). The development of novel models for studying IgG4 (patho)physiology and understanding how IgG4 responses are regulated could offer insights into novel treatment strategies for these IgG4-associated disease settings.

Do germinal centers protect most of us from becoming allergic?

OBJECTIVE

To review the literature and discuss a hypothesis as to why most people do not have allergy. This hypothesis is dependent on the following 3 main components: (1) airborne allergens (eg, from pollen or mites) are weak antigens that induce a B-cell response only in immunologically most reactive subjects (ie, with atopy); (2) a roadblock to production of immunoglobulin E (IgE) is the T helper 2/interleukin 4 requirement for class switch to IgE; (3) activated germinal centers prevent the formation of mature IgE-switched B-cells, creating a second roadblock to IgE production.

DATA SOURCES

Transgenic reporter mice and a cross-sectional human cohort.

STUDY SELECTIONS

From the mouse studies, we selected the data on histology and tissue-derived cell suspensions published by several groups in 2011 to 2014. From the human cohort, we selected our published microarray data on the levels of allergen-specific IgE and IgG in serum.

RESULTS

The immune response to airborne atopic allergens entails both IgE and IgG antibodies rather than just an IgG or IgE response. However, as expected for an immune response without mature germinal centers, the specific IgG levels will be very low, typically in the ng/ml range.

CONCLUSION

Control of IgE production is not just through the T helper 2/interleukin 4-mediated class switch. Recent studies suggest that mature germinal centers are likely to provide protection against the development of allergy to airborne allergens, as well. This may explain why allergen exposure does not induce allergen-specific IgE in everyone.

Allergische Reaktionen auf COVID-19-Impfungen – Was HNO-Ärzte wissen sollten – Teil 1: Allgemeine Aspekte von Allergien auf Impfstoffe, immunologische Grundlagen von Allergien auf Impfstoffe, Immunmechanismen von allergischen und pseudoallergischen Reaktionen, Teil 2: Charakteristiken der mRNA-Impfstoffe BNT162b2 und mRNA-1273 zur Prophylaxe von COVID-19 und assoziierte Immunphänomene, Teil 3: Praktische Aspekte der Prophylaxe, Diagnostik und Therapie von Allergien auf COVID-19-Impfstoffe

With BNT162b2 (approved in the EC on 27^th of December 2020) and mRNA-1273 (approved in the EC on 6^th of January 2021) for the first time ever two RNA-vaccines received conditional approval within the EC in order to effectively combat the SARS-COV2 pandemic. The emergence of sporadic cases of anaphylaxis following vaccination with these new compounds and the identification of PEGs (polyethylenglycols) as potential, widely used but yet usually unknown culprits have led to uncertainty among treating physicians and patients. The aim of this article series is to summarize current available pathophysiological and clinical information (part 1), to describe the characteristics of the vaccines (part 2) and to provide practical solutions for diagnosis and treatment of potential allergy against mRNACovid19 vaccines.

Further investigations of the IgE response to tetanus and diphtheria following covaccination with acellular rather than cellular Bordetella pertussis

BACKGROUND

It has previously been shown in an uncontrolled study that the IgE response to vaccine antigens is downregulated by co-vaccination with cellular Bordetella pertussis vaccine.

METHODS

In the present study, we compared in a controlled trial the humoral immune response to diphtheria toxoid (D) and tetanus toxoid (T) in relation to co-vaccinated cellular or acellular B pertussis vaccine. IgE, IgG4, and IgG to D and T were analyzed at 2, 7, and 12 months of age in sera of children vaccinated with D and T (DT, N = 68), cellular (DTPw, N = 68), 2- or 5-component acellular B pertussis vaccine (DTPa2, N = 64; DTPa5, N = 65).

RESULTS

One month after vaccination, D-IgE was detected in 10% sera of DTPw-vaccinated children, whereas vaccination in the absence of whole-cell pertussis resulted in 50%-60% IgE positivity. Six months after vaccination, the IgE antibody levels were found to be more persistent than the IgG antibodies. These diphtheria findings were mirrored by those for tetanus. Only minor differences between vaccine groups were found with regard to D-IgG and T-IgG. No immediate-type allergic reactions were observed.

CONCLUSION

Cellular (but not acellular) B pertussis vaccine downregulates IgE to co-vaccinated antigens in infants. We assume that the absence of immediate-type allergic reactions is due to the high levels of IgG antibodies competing with IgE antibodies.