The effects of atopy and asthma on in vivo human nasal responses to Toll-like receptor agonists
File(s)
Author(s)
Jha, Akhilesh
Type
Thesis
Abstract
Acute respiratory viral infections cause significant morbidity and mortality, especially in vulnerable individuals, and it is important to study viral pathogenesis and the host immune response in humans. Toll-like receptors (TLRs) play a critical role in the detection of viral nucleic acids, and airway TLR receptors respond to nucleic acid patterns in the RNA viruses that cause respiratory infections. However, a reliable method of measuring mucosal innate immune responses to viral infections is lacking. TLR3 agonists (poly(I:C) and poly-ICLC) and the combined TLR7/8 agonist (resiquimod, R848) are synthetic analogues of double stranded RNA (dsRNA) and single stranded RNA (ssRNA) respectively. Nasal challenge with these TLR agonists was carried out, and serial sampling using nasosorption and nasal curettage was performed. Mucosal immune responses were measured and the effect of different host factors (e.g. asthma) on these responses was studied.
Poly(I:C) and poly-ICLC were well tolerated but failed to induce significant and reliable nasal mucosal innate immune responses. R848 at a higher dose (10 µg/100 µL per nostril) induced significant mucosal interferon and cytokine responses but caused mild to moderate flu-like symptoms in three out of nine volunteers. A lower dose of R848 (0.02 µg/kg/100 µL, mean dose 1.5 µg/100 µL) was subsequently utilised in three groups of volunteers: healthy non-atopic (n=12), allergic rhinitis (n=12) and allergic asthma (n=11). This was well tolerated and induced significant release of nasal mucosal IFNs (IFN-α, IFN-γ), proinflammatory cytokines (TNF-α, IL-2, IL-12p70) and chemokines (CXCL10, CCL2, CCL3, CCL4 and CCL13) when compared to saline. Participants with allergic rhinitis and allergic asthma had similar IFN-α, CCL3 and CCL13 levels that were increased compared to healthy volunteers. In volunteers with atopy, baseline nasal mucosal gene expression of the anti-inflammatory secretoglobin SCGB1A1 had a strong negative correlation with subsequent innate immune activation by R848. Eight hours after R848 challenge, several mucosal IFN stimulated genes (ISGs) were upregulated (IFIT3, OAS2, IRF7, MX1, MYD88, DDX58 and STAT1) as well as SOCS1, TLR3, TLR7, KRT5 and CLEC4C, whilst IFNAR1 and ADGRG1 were downregulated. Volunteers with asthma had increased DDX58, MX1 and IFIT3 when compared to those with allergic rhinitis and healthy volunteers.
This research has led to the successful development of a non-invasive and well tolerated method to induce and precisely measure nasal mucosal innate immune responses to the ssRNA analogue and TLR7/8 agonist R848, and this methodology has been used to demonstrate heightened innate immune activation in volunteers with allergic rhinitis and asthma. This technique can be extended to examine responses in a range of host conditions and diseases as well as to assess the adjuvant potential of R848 in conjunction with mucosal vaccines targeted against infection and cancer.
Poly(I:C) and poly-ICLC were well tolerated but failed to induce significant and reliable nasal mucosal innate immune responses. R848 at a higher dose (10 µg/100 µL per nostril) induced significant mucosal interferon and cytokine responses but caused mild to moderate flu-like symptoms in three out of nine volunteers. A lower dose of R848 (0.02 µg/kg/100 µL, mean dose 1.5 µg/100 µL) was subsequently utilised in three groups of volunteers: healthy non-atopic (n=12), allergic rhinitis (n=12) and allergic asthma (n=11). This was well tolerated and induced significant release of nasal mucosal IFNs (IFN-α, IFN-γ), proinflammatory cytokines (TNF-α, IL-2, IL-12p70) and chemokines (CXCL10, CCL2, CCL3, CCL4 and CCL13) when compared to saline. Participants with allergic rhinitis and allergic asthma had similar IFN-α, CCL3 and CCL13 levels that were increased compared to healthy volunteers. In volunteers with atopy, baseline nasal mucosal gene expression of the anti-inflammatory secretoglobin SCGB1A1 had a strong negative correlation with subsequent innate immune activation by R848. Eight hours after R848 challenge, several mucosal IFN stimulated genes (ISGs) were upregulated (IFIT3, OAS2, IRF7, MX1, MYD88, DDX58 and STAT1) as well as SOCS1, TLR3, TLR7, KRT5 and CLEC4C, whilst IFNAR1 and ADGRG1 were downregulated. Volunteers with asthma had increased DDX58, MX1 and IFIT3 when compared to those with allergic rhinitis and healthy volunteers.
This research has led to the successful development of a non-invasive and well tolerated method to induce and precisely measure nasal mucosal innate immune responses to the ssRNA analogue and TLR7/8 agonist R848, and this methodology has been used to demonstrate heightened innate immune activation in volunteers with allergic rhinitis and asthma. This technique can be extended to examine responses in a range of host conditions and diseases as well as to assess the adjuvant potential of R848 in conjunction with mucosal vaccines targeted against infection and cancer.
Version
Open Access
Date Issued
2018-03
Date Awarded
2018-07
Advisor
Openshaw, Peter
Hansel, Trevor
Sponsor
National Institute for Health Research (Great Britain)
Imperial College London
Grant Number
P45058
Publisher Department
National Heart & Lung Institute
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)