CpG-containing immunostimulatory DNA sequences elicit TNF-alpha-dependent toxicity in rodents but not in humans.
CpG-containing immunostimulatory DNA sequences (ISS), which signal through TLR9, are being developed as a therapy for allergic indications and have proven to be safe and well tolerated in humans when administrated via the pulmonary route. In contrast, ISS inhalation has unexplained toxicity in rodents, which express TLR9 in monocyte/macrophage lineage cells as well as in plasmacytoid DCs (pDCs) and B cells, the principal TLR9-expressing cells in humans. We therefore investigated the mechanisms underlying this rodent-specific toxicity and its implications for humans. Mice responded to intranasally administered 1018 ISS, a representative B class ISS, with strictly TLR9-dependent toxicity, including lung inflammation and weight loss, that was fully reversible and pDC and B cell independent. Knockout mouse experiments demonstrated that ISS-induced toxicity was critically dependent on TNF-alpha, with IFN-alpha required for TNF-alpha induction. In contrast, human PBMCs, human alveolar macrophages, and airway-derived cells from Ascaris suum-allergic cynomolgus monkeys did not produce appreciable TNF-alpha in vitro in response to ISS stimulation. Moreover, sputum of allergic humans exposed to inhaled ISS demonstrated induction of IFN-inducible genes but minimal TNF-alpha induction. These data demonstrate that ISS induce rodent-specific TNF-alpha-dependent toxicity that is absent in humans and reflective of differential TLR9 expression patterns in rodents versus humans.
Campbell
John D
JD
Dynavax Technologies Corporation, Berkeley, California 94710, USA. DCampbell@dynavax.com
Cho
Yan
Y
Foster
Martyn L
ML
Kanzler
Holger
H
Kachura
Melissa A
MA
Lum
Jeremy A
JA
Ratcliffe
Marianne J
MJ
Sathe
Atul
A
Leishman
Andrew J
AJ
Bahl
Ash
A
McHale
Mark
M
Coffman
Robert L
RL
Hessel
Edith M
EM
D000276:Adjuvants, Immunologic / Q000633:toxicity; D000280:Administration, Inhalation; D000818:Animals; D001249:Asthma / Q000235:genetics / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D008252:Macaca fascicularis; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009838:Oligodeoxyribonucleotides / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology / Q000633:toxicity*; D013045:Species Specificity; D051217:Toll-Like Receptor 9 / Q000819:agonists / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D000276:Adjuvants, Immunologic; D016207:Cytokines; D009838:Oligodeoxyribonucleotides; C495371:TLR9 protein, human; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha; C489630:1018 oligonucleotide