Supplementary Material for: Intranasal Administration of CpG Induces a Rapid and Transient Cytokine Response Followed by Dendritic and Natural Killer Cell Activation and Recruitment in the Mouse Lung

CpG-containing oligodeoxynucleotides are potent mucosal adjuvants and
effective as stand-alone treatment of respiratory infections in mice.
Although CpG is also used as a type 1 helper immunomodulator in the
treatment of asthma and allergic disease, immune modulation following
intranasal application has not been fully characterized yet. Using a
B-type CpG, we monitored RNA expression profiles, cytokine production
and cellular activation in lung tissue and bronchoalveolar lavages ex
vivo and cytokine production of purified cell populations in vitro. CpG
triggered the upregulation of many transcripts, including interferon
response genes and proinflammatory cytokine genes, between 3 h and 4
days. Overlapping subsets of these cytokine proteins were induced in
vitro in purified CD11c+ cells, B cells and alveolar macrophages from
the lung, thus identifying these cells as direct targets of CpG. While
lung B cells strongly respond to CpG in vitro, less activation is found
ex vivo, suggesting efficient CpG sequestering or rapid B cell migration
after activation. In contrast, a type II alveolar epithelial cell line
did not respond to CpG in vitro. We noted selective recruitment of
plasmacytoid dendritic cells (DCs) into the lung tissue, and of
conventional DCs and natural killer (NK) cells into the lung tissue and
bronchoalveolar space. Furthermore, CpG induced activation of
intrapulmonary DCs, NK and T cells. We hypothesize that CpG-linked
adjuvanticity and clearance of respiratory pathogens are mediated by two
major mechanisms: transient induction of the interferon pathway
limiting microbial survival and selective recruitment of DCs and NK
cells, which allows for better adaptive responses.