TLR4 signaling in effector CD4+ T cells regulates TCR activation and experimental colitis in mice
José M. González-Navajas, … , Jongdae Lee, Eyal Raz
José M. González-Navajas, … , Jongdae Lee, Eyal Raz
Published January 4, 2010
Citation Information: J Clin Invest. 2010;120(2):570-581. https://doi.org/10.1172/JCI40055.
View: Text | PDF
Research Article Immunology

TLR4 signaling in effector CD4+ T cells regulates TCR activation and experimental colitis in mice

Abstract

TLRs sense various microbial products. Their function has been best characterized in DCs and macrophages, where they act as important mediators of innate immunity. TLR4 is also expressed on CD4+ T cells, but its physiological function on these cells remains unknown. Here, we have shown that TLR4 triggering on CD4+ T cells affects their phenotype and their ability to provoke intestinal inflammation. In a model of spontaneous colitis, Il10–/–Tlr4–/– mice displayed accelerated development of disease, with signs of overt colitis as early as 8 weeks of age, when compared with Il10–/– and Il10–/–Tlr9–/– mice, which did not develop colitis by 8 months. Similar results were obtained in a second model of colitis in which transfer of naive Il10–/–Tlr4–/– CD4+ T cells into Rag1–/– recipients sufficient for both IL-10 and TLR4 induced more aggressive colitis than the transfer of naive Il10–/– CD4+ T cells. Mechanistically, LPS stimulation of TLR4-bearing CD4+ T cells inhibited ERK1/2 activation upon subsequent TCR stimulation via the induction of MAPK phosphatase 3 (MKP-3). Our data therefore reveal a tonic inhibitory role for TLR4 signaling on subsequent TCR-dependent CD4+ T cell responses.

Authors

José M. González-Navajas, Sean Fine, Jason Law, Sandip K. Datta, Kim P. Nguyen, Mandy Yu, Maripat Corr, Kyoko Katakura, Lars Eckman, Jongdae Lee, Eyal Raz

×

Figure 5

TLR4 signaling in CD4+ T cells downregulates IFN-γ production through ERK1/2 inhibition.

Options: View larger image (or click on image) Download as PowerPoint
TLR4 signaling in CD4+ T cells downregulates IFN-γ production through ER...
(A) Splenic CD4+ T cells from OT-II mice were incubated for 2 hours in the presence of 100 ng/ml LPS or medium alone. The cells were then washed and cultured for 5 days with OVA-loaded BMDCs. After coculture, the CD4+ cells were restimulated, and the secretion of cytokines was determined 24 hours later. (B) NF-κB activation was assessed in nuclear extracts by EMSA. (C) Cytosolic lysates were immunoblotted for MAPK protein activation after anti-CD3/CD28 Ab stimulation with or without LPS (100 ng/ml) for 2 hours prior to TCR stimulation. (D) LPS-dependent regulation of ERK1/2 phosphorylation was confirmed by phospho-protein analysis by flow cytometry as described in Methods. Numbers within histograms denote the percentage of p-ERK1/2–positive cells in stimulated cells when compared with control cells. (E) Activation of NFAT-1 was measured by immunoblotting of nuclear extracts from CD4+ cells stimulated as in C. (F) RT-PCR analysis of CD4+ T cells incubated with the MEK/ERK1/2 inhibitor UO126 or vehicle (DMSO) before being stimulated with anti-CD3/CD28 Abs for the indicated times. Data in A–F represent mean ± SEM of 3 independent experiments. *P < 0.05. All experiments, except in A, were carried out with FACS-sorted MLN-derived CD4+ cells from Il10–/– mice (purity, >98%).