Suppressed IgG4 class switching in dupilumab- and TNF inhibitor-treated patients after repeated SARS-CoV-2 mRNA vaccination

Background Repeated mRNA vaccination against SARS-CoV-2 has been shown to induce class switching to IgG4, a non-inflammatory human antibody subclass linked to tolerance. Although poorly understood, prolonged antigenic stimulation and IL-4 signalling may be instrumental in IgG4 switching. We and others have previously shown that widely used immunosuppressive drugs such as methotrexate (MTX) and TNF inhibitors (TNFi) have a minor inhibitory impact on humoral SARS-CoV-2 mRNA vaccination responses. However, the impact of such immunosuppressive drugs on IgG4 switching is unknown. Aim To study the impact of widely used immunosuppressive drugs (TNFi, MTX, or the IL-4 receptor-blocking antibody dupilumab on IgG4 skewing upon repeated SARS-CoV-2 mRNA vaccination. Methods Antibody responses to the receptor-binding domain (RBD) of the spike protein upon repeated SARS-CoV-2 mRNA vaccination were measured in 604 individuals including patients with immune-mediated inflammatory diseases treated with TNFi and/or MTX, or dupilumab, as well as healthy controls and untreated patients. Results We observed a substantial increase in the proportion of RBD-specific IgG4 antibodies (median 21%) in healthy/untreated controls after a third mRNA vaccination. This IgG4 skewing was absent when primary vaccination was adenoviral vector-based and was profoundly reduced in both dupilumab- and TNFi-treated patients (<1%), but only moderately in patients treated with MTX (7%). Conclusion Our results imply a major role for both IL-4/IL-13 as well as TNF in IgG4 class switching. These novel findings advance our understanding of IgG4 class switch dynamics, and may benefit future mRNA vaccine strategies, humoral tolerance induction, as well as treatment of IgG4 pathologies. ### Competing Interest Statement FE and TWK report (governmental) grants from ZonMw to study immune response after SARS-Cov-2 vaccination in autoimmune diseases. FE also reports grants from Prinses Beatrix Spierfonds, CSL Behring, Kedrion, Terumo BCT, Grifols, Takeda Pharmaceutical Company, and GBS-CIDP Foundation; consulting fees from UCB Pharma and CSL Behring; and honoraria from Grifols. PIS is involved in clinical trials with many pharmaceutical industries that manufacture drugs used for the treatment of, for example, psoriasis and atopic dermatitis, for which financial compensation is paid to the department or hospital, and is a chief investigator of the TREAT NL registry taskforce and SECURE-AD registry. MWB is a secretary for the Dutch Experimental Dermatology Board; head of the pigmentary disorders group within the Dutch Dermatology Board; and reports honoraria from Pfizer, Sanofi, Novartis, and Fondation Rene Touraine. JK has speaking relationships with Merck Serono, Biogen Idec, TEVA, Sanofi, Genzyme, Roche, and Novartis; received financial support to his institution for research activities from Merck Serono, Bayer Shcering Pharma, Biogen Idec, GlaxoSmithKline (GSK), Roche, Teva, Sanofi, Genzyme, and Novartis. BH reports unpaid positions as a medical adviser for several patient groups, a board position for ERN-SKIN, and associate editor for The British Journal of Dermatology; reports grants from AbbVie, Akari Therapeutics, Celgene, and Novartis; consulting fees from UCB Pharma, Novartis, and Janssen; and honoraria from AbbVie. DJH reports grants from AbbVie, AstraZeneca, Janssen, LEO Pharma, and UCB; honoraria from AbbVie, Galderma, Janssen, Lilly, Pfizer, Sanofi, and UCB; and a paid position on an advisory board for BIOMAP IMI. All other authors declare no competing interests. ### Funding Statement This study was supported by ZonMw (The Netherlands Organization for Health Research and Development), project number 10430072010007. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the medical ethical committee of the Amsterdam UMC (2020.194; trial registry NL74974.018.20 and EudraCT 2021-001102-30). All participants provided written informed consent. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript