Abstract
The efficacy of a vaccine is generally dependent on an adjuvant, which enhances the immune functions and alum has been widely used in human immunization. Alum activates the intracellular stress sensors inflammasomes, but whether these are responsible for the adjuvanticity is controversial. The objectives of this investigation were to examine the hypothesis that alum-mediated adjuvanticity is a function of stress and conversely that stress agents will elicit adjuvanticity. The investigation was carried out in BALB/c mice by SC immunization with ovalbumin (OVA) mixed with alum. This elicited inflammasomes, with significant activation of caspase 1, production of IL-1β, and adjuvanticity, demonstrated by enhancing OVA-specific serum IgG antibodies, CD4(+) T cells, and proliferation. The novel finding that alum induced HSP70 suggests that stress is involved in the mechanism of adjuvanticity. This was confirmed by inhibition studies with PES (phenylethynesulfonamide), which disrupts inducible HSP70 function, and inhibited both inflammasomes and the adjuvant function. Parallel studies were pursued with an oxidative agent (sodium arsenite), K-releasing agent (Gramicidin) and a metal ionophore (dithiocarbamate). All 3 stress agents induced HSP70, inflammasomes, and the adjuvant functions. Furthermore, up-regulation of membrane associated IL-15 on DC and CD40L on T cells in the animals treated with alum or the stress agents mediate the interactions between splenic CD11c DC and CD4(+) or CD8(+) T cells. The results suggest that the three stress agents elicit HSP70, a hallmark of stress, as well as inflammasomes and adjuvanticity, commensurate with those of alum, which may provide an alternative strategy in developing novel adjuvants.
Highlights
Up-regulation of membrane associated IL-15 on DC and CD40L on T cells in the animals treated with alum or the stress agents mediate the interactions between splenic CD11c DC and CD4؉ or CD8؉ T cells
The results suggest that the three stress agents elicit HSP70, a hallmark of stress, as well as inflammasomes and adjuvanticity, commensurate with those of alum, which may provide an alternative strategy in developing novel adjuvants
Reagents—Goat anti-mouse IL-15 antibodies were obtained from R&D (Abingdon, UK), anti-HSP70 antibodies from Stressgen (US) and antibodies to mouse CD11c, CD4, CD8, CD44, CD40L and CD62L were purchased from BD Biosciences (Oxford, UK)
Summary
The investigation was carried out in BALB/c mice by SC immunization with ovalbumin (OVA) mixed with alum This elicited inflammasomes, with significant activation of caspase 1, production of IL-1, and adjuvanticity, demonstrated by enhancing OVA-specific serum IgG antibodies, CD4؉ T cells, and proliferation. We examined this paradigm in vivo and tested the requirement of inducible HSP70 for expression of inflammasome and adjuvanticity by inhibition with PES (phenylethynesulfonamide), specific for inducible HSP70 [21] This in turn led us to investigate in vivo 3 diverse stress agents to ascertain if they function as adjuvants and express the immune functions demonstrated with alum. We selected an oxidative agent (sodium arsenite), K releasing (Gramicidin), and a heavy metal ionophore (dithiocarbamate) for their potential adjuvanticity in comparison with alum These differ in their properties, they act as stress agents that reactivate quiescent HSV-1 viral genomes [22] and they have been used in clinical practice. The 3 stress agents elicit inflammasomes and adjuvanticity commensurate with that of alum
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
