TLR8 deficiency leads to autoimmunity in mice
Olivier Demaria, Philippe P. Pagni, Stephanie Traub, Aude de Gassart, Nora Branzk, Andrew J. Murphy, David M. Valenzuela, George D. Yancopoulos, Richard A. Flavell, Lena Alexopoulou
Olivier Demaria, Philippe P. Pagni, Stephanie Traub, Aude de Gassart, Nora Branzk, Andrew J. Murphy, David M. Valenzuela, George D. Yancopoulos, Richard A. Flavell, Lena Alexopoulou
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Research Article Autoimmunity

TLR8 deficiency leads to autoimmunity in mice

Abstract

TLRs play an essential role in the induction of immune responses by detecting conserved molecular products of microorganisms. However, the function of TLR8 is largely unknown. In the current study, we investigated the role of TLR8 signaling in immunity in mice. We found that Tlr8–/– DCs overexpressed TLR7, were hyperresponsive to various TLR7 ligands, and showed stronger and faster NF-κB activation upon stimulation with the TLR7 ligand R848. Tlr8–/– mice showed splenomegaly, defective development of marginal zone (MZ) and B1 B cells, and increased serum levels of IgM and IgG2a. Furthermore, Tlr8–/– mice exhibited increased serum levels of autoantibodies against small nuclear ribonucleoproteins, ribonucleoprotein, and dsDNA and developed glomerulonephritis, whereas neither Tlr7–/– nor Tlr8–/–Tlr7–/– mice showed any of the phenotypes observed in Tlr8–/– mice. These data provide evidence for a pivotal role for mouse TLR8 in the regulation of mouse TLR7 expression and prevention of spontaneous autoimmunity.

Authors

Olivier Demaria, Philippe P. Pagni, Stephanie Traub, Aude de Gassart, Nora Branzk, Andrew J. Murphy, David M. Valenzuela, George D. Yancopoulos, Richard A. Flavell, Lena Alexopoulou

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Figure 3

Increased TLR7 expression and NF-κB activation in Tlr8–/– BMDCs.

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Increased TLR7 expression and NF-κB activation in Tlr8–/– BMDCs. WT ...
WT and Tlr8–/– BMDCs were left untreated or stimulated with 50 nM (A and B) or 100 nM (C and H) R848 for the indicated times. Total mRNA was extracted from the cells, and the expression of (A) Tlr8 or (B) Tlr7 was assessed by Q-PCR. Total protein lysates were prepared, and (C) the expression of Tlr7 and β-actin were assessed at 0, 4, and 8 hours after stimulation, or (H) phosphorylation of NF-κBp65 was determined by Western blot. Total NF-κBp65 and β-actin were used as loading controls. (D–F) WT and Tlr8–/– BMMs were left untreated or stimulated with 50 nM R848. At the indicated time points, either total mRNA was extracted from the cells and the expression of (D) Tlr8 and (E) Tlr7 was assessed by Q-PCR, or (F) total protein lysates were prepared, and the expression of Tlr7 and β-actin were assessed by Western blot. (G) Tlr8–/– BMDCs were transfected with 50 pmol Tlr8-FLAG or GFP mRNA. 5 hours later, cells were harvested, total protein lysates were prepared, and the expression of Tlr7, Tlr8-FLAG, and β-actin were assessed by Western blot. The Tlr7/β-actin ratio is shown at right. (A, B, D, and E) Data are mean ± SD of duplicates and are representative of 2–3 independent experiments. (C, F, G, and H) Data are representative of 3–5 (C, F, and H) or 2 (G) independent experiments.