Gonadal androgens are associated with decreased type I interferon production by plasmacytoid dendritic cells and increased IgG titres to BNT162b2 following co-vaccination with live attenuated influenza vaccine in adolescents

Abstract

mRNA vaccine technologies introduced following the SARS-CoV-2 pandemic have highlighted the need to better understand the interaction of adjuvants and the early innate immune response. Type I interferon (IFN-I) is an integral part of this early innate response that primes several components of the adaptive immune response. Women are widely reported to respond better than men to tri- and quadrivalent influenza vaccines. Plasmacytoid dendritic cells (pDCs) are the primary cell type responsible for IFN-I production, and female pDCs produce more IFN-I than male pDCs since the upstream pattern recognition receptor Toll-like receptor 7 (TLR7) is encoded by X chromosome and is biallelically expressed by up to 30% of female immune cells. Additionally, the TLR7 promoter contains several putative androgen response elements, and androgens have been reported to suppress pDC IFN-I in vitro. Unexpectedly, therefore, we recently observed that male adolescents mount stronger antibody responses to the Pfizer BNT162b2 mRNA vaccine than female adolescents after controlling for natural SARS-CoV-2 infection. We here examined pDC behaviour in this same cohort to determine the impact of IFN-I on anti-spike and anti-receptor-binding domain IgG titres to BNT162b2. Through flow cytometry and least absolute shrinkage and selection operator (LASSO) modelling, we determined that serum-free testosterone was associated with reduced pDC IFN-I, but contrary to the well-described immunosuppressive role for androgens, the most bioactive androgen dihydrotestosterone was associated with increased IgG titres to BNT162b2. Also unexpectedly, we observed that co-vaccination with live attenuated influenza vaccine boosted the magnitude of IgG responses to BNT162b2. Together, these data support a model where systemic IFN-I increases vaccine-mediated immune responses, yet for vaccines with intracellular stages, modulation of the local IFN-I response may alter antigen longevity and consequently improve vaccine-driven immunity.

Keywords: adolescent vaccination; androgen; immune sex difference; plasmacytoid dendritic cell; type I interferon.

Figure 1

pDC activation following BNT162b2 +/− LAIV co-vaccination. pDC flow cytometry data following whole blood TLR7 stimulation for the day of vaccination (D0) and the following day (D1) (n = 18; male = 7, female = 11. (A) Percentage of pDCs of live PBMCs. (B) MFI of pDC CD123. (C) MFI of pDC HLA-DR. (D) Percentage of IFN-α+ pDCs. (E) MFI of pDC IFN-α. (F) percentage of pDC TNF-α. (G) MFI of pDC TNF-α. Pairwise comparisons via paired Student’s t-test. pDC, plasmacytoid dendritic cell; LAIV, live attenuated influenza vaccine; PBMCs, peripheral blood mononuclear cells; MFI, mean fluorescence intensity.

Figure 2

Sex differential pDC activation following BNT162b2 +/− LAIV co-vaccination. Sex-stratified pDC flow cytometry data following whole blood TLR7 stimulation for the day of vaccination (D0) (n = 33; male = 18, female = 15) and the following day (D1) (n = 18; male = 7, female = 11). (A) Percentage of pDCs of live PBMCs. (B) MFI of pDC CD123. (C) MFI of pDC HLA-DR. (D) Percentage of IFN-α+ pDCs. (E) MFI of pDC IFN-α. (F) Percentage of pDC TNF-α. (G) MFI of pDC TNF-α. Pairwise comparisons via unpaired Student’s t-test with Bonferroni’s correction for multiple comparisons. pDC, plasmacytoid dendritic cell; LAIV, live attenuated influenza vaccine; PBMCs, peripheral blood mononuclear cells; MFI, mean fluorescence intensity.

Figure 3

Serum gonadal androgen measurements in adolescent men and women. Serum androgen concentrations determined via tandem mass spectrometry for adolescents (n = 33; male = 18, female = 15). (A–D) Comparison of serum concentrations in men and women for testosterone, free testosterone, dihydrotestosterone (DHT), and androstenedione, respectively. (E–H) Correlation of androgen concentration with age for men and women for testosterone, free testosterone, DHT, and androstenedione, respectively. Pairwise comparisons via Student’s unpaired t-test. Correlations via Pearson’s method.

Figure 4

Serum adrenal androgen measurements in adolescent men and women. Serum androgen concentrations determined via tandem mass spectrometry for adolescents (n = 33; male = 18, female = 15). (A–E) Comparison of serum concentrations in men and women for dehydroepiandrosterone (DHEA), 11-hydroxyandrostenedione (11OHA4), 11-ketoandrostenedione (11KA4), 11-ketotestosterone (11KT), and 11-hydroxytestosterone (11OHT), respectively. (F–J) Correlation of androgen concentration with age for men and women for DHEA, 11OHA4, 11KA4, 11KT, and 11OHT, respectively. Pairwise comparisons via Student’s unpaired t-test. Correlations via Pearson’s method.