Repository logo
 

Identification of immunostimulatory adjuvant(s) that will promote a Th17-type of immune response

Date

2017-07-12

Journal Title

Journal ISSN

Volume Title

Publisher

ORCID

0000-0002-2282-9210

Type

Thesis

Degree Level

Masters

Abstract

Immunostimulatory adjuvants are substances added to vaccines to promote and direct a robust Th1, Th2, or Th17 immune response. Murine Th17 cells are produced and differentiated from naïve T cells in the presence of transforming growth factor (TGF)-β and interleukin (IL)-6 and once differentiated, Th17 cells produce cytokines IL-17A, IL-17F, IL-21 and IL-22. We investigated how immunostimulatory molecules such as poly[di(sodium carboxylatoethylphenoxy)-phosphazene (PCEP), Alum, CpG oligodeoxynucleotide (CpG ODN), Curdlan, Leptin and Lipopolysaccharide (LPS), alone or in combination influenced differentiation and/or activation of Th17 type immune cells in mice. In vitro studies showed that murine splenocytes stimulated with CpG showed significantly induced production of IL-12, a cytokine important for induction of Th1 type immune cells and IL-12 is known to be inhibitory for differentiation of Th17-type immune cells. Curdlan + Leptin +/- PCEP and PCEP + Curdlan induced significant expression of TGF-β. No immunostimulant combination induced both IL-6 and TGF-β, which we anticipated would be required for Th17 cell differentiation. When we investigated the cytokines induced by the immunostimulants 48 hours after injection in muscle tissue, we determined that Curdlan + Leptin significantly induced production of IL-17, likely from activation of already differentiated T cells. TGF-β was significantly induced in response to Curdlan and Leptin, alone and in combination but they were poor inducers of IL-6. PCEP+/- CpG or LPS significantly induced expression of IL-6 but not TGF-β. Finally, we immunized mice via intramuscular (i.m.) route with OVA in the presence of the immunostimulatory adjuvants and assessed cytokine production from OVA-restimulated splenocytes 5 weeks later. ELISA results indicated that OVA-specific IL-17 production was significantly induced in splenocytes from mice immunized with PCEP + OVA relative to the mice immunized with Curdlan + OVA, although it was insignificant with respect to the OVA immunization group presumably due to the highly variable responses. Using flow cytometric analysis, we observed that vaccination with PCEP + OVA and Curdlan + Leptin + OVA significantly induced the frequency of OVA-specific splenic CD4+IL-17+ cells. Curdlan + Leptin also significantly induced the frequency of OVA-specific CD4+Foxp3+ cells and CD4+IL-17+Foxp3+ double positive cells. Thus, we conclude that in vitro studies are poorly predictive of the type of adaptive response that may be induced when immunostimulatory adjuvants were used in a vaccine. Furthermore, vaccines formulated with PCEP and Curdlan + Leptin adjuvants promote Th17 cell differentiation and should be investigated as a combinational adjuvant for bacteria or fungal based immunizations.

Description

Keywords

Adjuvant, Th17

Citation

Degree

Master of Science (M.Sc.)

Department

School of Public Health

Program

Vaccinology and Immunotherapeutics

Part Of

item.page.relation.ispartofseries

DOI

item.page.identifier.pmid

item.page.identifier.pmcid