CpG-containing immunostimulatory DNA sequences elicit TNF-α–dependent toxicity in rodents but not in humans
John D. Campbell, … , Robert L. Coffman, Edith M. Hessel
John D. Campbell, … , Robert L. Coffman, Edith M. Hessel
Published August 10, 2009
Citation Information: J Clin Invest. 2009;119(9):2564-2576. https://doi.org/10.1172/JCI38294.
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Research Article Immunology

CpG-containing immunostimulatory DNA sequences elicit TNF-α–dependent toxicity in rodents but not in humans

Abstract

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-α, with IFN-α required for TNF-α induction. In contrast, human PBMCs, human alveolar macrophages, and airway-derived cells from Ascaris suum–allergic cynomolgus monkeys did not produce appreciable TNF-α 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-α induction. These data demonstrate that ISS induce rodent-specific TNF-α–dependent toxicity that is absent in humans and reflective of differential TLR9 expression patterns in rodents versus humans.

Authors

John D. Campbell, Yan Cho, Martyn L. Foster, Holger Kanzler, Melissa A. Kachura, Jeremy A. Lum, Marianne J. Ratcliffe, Atul Sathe, Andrew J. Leishman, Ash Bahl, Mark McHale, Robert L. Coffman, Edith M. Hessel

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Figure 5

TNF-α is crucial for 1018 ISS–induced toxicity.

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TNF-α is crucial for 1018 ISS–induced toxicity. Knockout and wild-type m...
Knockout and wild-type mice were treated with 5 mg/kg 1018 ISS or saline i.n. and sacrificed 24 hours later. Weight was measured for TNF-α–/– (A), p55/p75–/– (B), and p75–/– (C) and wild-type mice both at 1018 ISS administration and 24 hours later, and change in weight (mean ± SEM) was calculated. (D) BALF cytokines (mean ± SEM) in TNF-α–/– and wild-type mice were measured by ELISA. Dotted lines indicate minimum detection levels for the ELISA assay. n = 5 per group.