pubmed.ncbi.nlm.nih.gov

Cutting edge: roles of Toll-like receptor 4 and IL-23 in IL-17 expression in response to Klebsiella pneumoniae infection - PubMed

  • ️Wed Jan 01 2003

Cutting edge: roles of Toll-like receptor 4 and IL-23 in IL-17 expression in response to Klebsiella pneumoniae infection

Kyle I Happel et al. J Immunol. 2003.

Abstract

Local production of IL-17 is a significant factor in effective host defense against Gram-negative bacteria. However, the proximal events mediating IL-17 elaboration by T cells remain unclear. In this study, we show in vivo that intact Toll-like receptor 4 signaling in the lung is required for induction of both the p19 transcript of IL-23 and IL-17 protein elaboration in response to Klebsiella pneumoniae. Although IL-17 is widely considered a CD4(+) T cell product, we also demonstrate significant in vitro IL-17 production by CD8(+) T cells after culture in medium from dendritic cells exposed to these bacteria. The dominant portion of this IL-17-inducing activity for both CD4(+) and CD8(+) T cells is IL-23. These data demonstrate the critical signaling pathway for IL-17 induction in the host response to Gram-negative pulmonary infection and suggest a direct role for IL-23 in CD8(+) T cell IL-17 production.

PubMed Disclaimer

Figures

FIGURE 1
FIGURE 1

LPS-insensitive C3H/HeJ mice display markedly reduced IL-17 production and delayed p19 mRNA expression in response to i.t. challenge with K. pneumoniae. A, BAL fluid IL-17 protein content at the time of bacterial inoculation and 4 and 16 h later. B, Copy number of IL-17 mRNA transcripts in whole lung homogenate at the same time points, as measured by quantitative real-time RT-PCR. Copy numbers are normalized to 18s rRNA content for internal control. C, Lung homogenate mRNA transcripts for the p19 subunit of IL-23. C3H/HeJ mice show a blunted and delayed induction of p19 transcripts (note the separate y-axis for 16-h data for p19 mRNA; n = 6 per group; *, p < 0.05 compared with C3H/HeN group at the same time point for all three figures).

FIGURE 2
FIGURE 2

The presence of both CD4+ and CD8+ T cells is necessary for normal IL-17 production in response to K. pneumoniae. Ab depletion of CD4+ or CD8+ T cells reduces the IL-17 content in BAL fluid from C57/BL6 mice 24 h after i.t. challenge. Combined neutralization results in significant abrogation of detectable IL-17 (n = 6 per group; *, p < 0.05 compared with Ab-untreated animals).

FIGURE 3
FIGURE 3

In vitro coculture of total spleen T cells (CD90+) with K. pneumoniae-pulsed DC. A, Twenty-four-hour cell culture supernatant analysis confirms that C3H/HeJ-derived cells exhibit diminished IL-17 expression compared with that of C3H/HeN cells. B, IL-17 mRNA transcripts by quantitative real-time RT-PCR of the same experiment (n = 6 per group; *, p < 0.05 compared with C3H/HeN mice).

FIGURE 4
FIGURE 4

In vitro DC/T cell physical contact is not required for IL-17 production in response to K. pneumoniae. CD8+ T cells produce more IL-17 protein and mRNA transcripts compared with those of CD4+ T cells in response to bacteria-pulsed DC. A, IL-17 in cell culture supernatant after 24 h of culture in each of the following conditions: A, T cell only plus bacteria; B, DC only plus bacteria; C, DC plus bacteria plus membrane barrier insert containing T cells; D, DC plus bacteria plus T cells without barrier; E, DC plus T cell without barrier or bacteria. B, IL-17 mRNA transcripts from total cell pellets of the same experimental groups (n = 4 per group; *, p < 0.05 compared with CD8+ cells of same exposure condition and to CD4+ T cells in condition A; ‡, p < 0.05 compared with CD8+ T cells in condition A).

FIGURE 5
FIGURE 5

CD4+ and CD8+ T cell IL-17 response to conditioned medium from K. pneumoniae-pulsed DC requires biologically active IL-23. A, Conditioned medium from p35−/− (knockout (K/O)) DC (devoid of IL-12) elicits an augmented IL-17 response from CD4+ and CD8+ T cells, whereas medium from p40−/− DC (devoid of IL-12 and IL-23) shows marked attenuation in comparison to wild type (WT). Neutralization of conditioned medium with anti-p40 also showed significantly less IL-17 induction in both CD4+ and CD8+ T cells. B, IL-17 mRNA copy number from T cells of the same experiment (n = 6 per group; columns with different uppercase (CD4+) or lowercase (CD8+) letters denote statistical significance (p < 0.05) compared with different letters of the same case).

Similar articles

Cited by

References

    1. Aggarwal S, Gurney AL. IL-17: prototype member of an emerging cytokine family. J Leukocyte Biol. 2002;71:1. - PubMed
    1. Infante-Duarte C, Horton HF, Byrne MC, Kamradt T. Microbial lipopeptides induce the production of IL-17 in Th cells. J Immunol. 2000;165:6107. - PubMed
    1. Fossiez F, Djossou O, Chomarat P, Flores-Romo L, Ait-Yahia S, Maat C, Pin JJ, Garrone P, Garcia E, Saeland S, et al. T cell interleukin-17 induces stromal cells to produce proinflammatory and hematopoietic cytokines. J Exp Med. 1996;183:2593. - PMC - PubMed
    1. Ye P, Rodriguez FH, Kanaly S, Stocking KL, Schurr J, Schwarzenberger P, Oliver P, Huang W, Zhang P, Zhang J, et al. Requirement of interleukin 17 receptor signaling for lung CXC chemokine and granulocyte colony-stimulating factor expression, neutrophil recruitment, and host defense. J Exp Med. 2001;194:519. - PMC - PubMed
    1. Chabaud M, Fossiez F, Taupin JL, Miossec P. Enhancing effect of IL-17 on IL-1-induced IL-6 and leukemia inhibitory factor production by rheumatoid arthritis synoviocytes and its regulation by Th2 cytokines. J Immunol. 1998;161:409. - PubMed

Publication types

MeSH terms

Substances