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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. Interferon type I (IFN-I) is an integral part of this early innate response and can prime several components of the adaptive immune response. Females are widely reported to respond better than males to seasonal tri- and quad-valent 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 receptor TLR7 is encoded by the X-chromosome and is biallelically expressed by up to 30% of female immune cells. Additionally, the TLR7 promoter contains putative androgen response elements and androgens have been reported to suppress pDC IFN-Iin-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 cohort to determine the impact of IFN-I on anti-Spike and anti-receptor-binding domain titres to BNT162b2. Through 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 more potent 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 increased vaccine-mediated immune responses, but for vaccines with intracellular stages, modulation of the local IFN-I response may alter antigen longevity and consequently vaccine-driven immunity.Author SummaryType I interferons (IFN-I) are potent antiviral proteins which play a central role in activating t

Type 2 diabetes is characterized by diminished or inappropriate secretion of insulin, which could be a defect of either islet cell function or beta-cell mass. Quantitation of islet cell populations in postmortem pancreas demonstrates little change of beta-cell mass in type 2 diabetes. Reduction of islet cell mass (up to 30%) is associated largely with islet amyloid deposition, and the degree of amyloidosis is independent of the duration of the disease. Insulin secretory capacity is dependent on both function and mass of cells. beta-Cell secretion is heterogeneous; increasing glucose concentrations result in recruitment of beta-cells into the secretory pool, indicating a large reserve of secretory capacity that can be recruited in insulin resistant conditions. The Starling curve of islet function describes the relationship of insulin secretion to increasing levels of insulin resistance and hyperglycemia in type 2 diabetes. Longitudinal studies in Macaca mulatta monkeys show that insulin resistance is accompanied by increased islet mass and onset of diabetes is associated with deposition of amyloid and reduction of beta-cells. Increasing the function of unresponsive beta-cells rather than the mass of cells may be a more effective therapeutic target for type 2 diabetes.