This site needs JavaScript to work properly. Please enable it to take advantage of the complete set of features!
Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

NIH NLM Logo
Log in
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2007 Jun 11;204(6):1395-403.
doi: 10.1084/jem.20070234. Epub 2007 May 21.

Selective suppression of dendritic cell functions by Mycobacterium ulcerans toxin mycolactone

Affiliations
Comparative Study

Selective suppression of dendritic cell functions by Mycobacterium ulcerans toxin mycolactone

Emmanuelle Coutanceau et al. J Exp Med. .

Abstract

Mycolactone is a polyketide toxin produced by Mycobacterium ulcerans (Mu), the causative agent of the skin disease Buruli ulcer (BU). Surprisingly, infected tissues lack inflammatory infiltrates. Structural similarities between mycolactone and immunosuppressive agents led us to investigate the immunomodulatory properties of mycolactone on dendritic cells (DCs), the key initiators and regulators of immune responses. At noncytotoxic concentrations, phenotypic and functional maturation of both mouse and human DCs was inhibited by mycolactone. Notably, mycolactone blocked the emigration of mouse-skin DCs to draining lymph nodes, as well as their maturation in vivo. In human peripheral blood-derived DCs, mycolactone inhibited the ability to activate allogeneic T cell priming and to produce inflammatory molecules. Interestingly, production of the cytokines interleukin (IL) 12, tumor necrosis factor alpha, and IL-6 was only marginally affected, whereas production of the chemokines macrophage inflammatory protein (MIP) 1alpha, MIP-1beta, regulated on activation, normal T cell expressed and secreted, interferon gamma-inducible protein 10, and monocyte chemoattractant protein 1 was abolished at nanomolar concentrations. Importantly, mycolactone endogenously expressed by Mu mediated similar inhibitory effects on beta-chemokine production by DCs. In accordance with the histopathological features of BUs, our results suggest that bacterial production of mycolactone may limit both the initiation of primary immune responses and the recruitment of inflammatory cells to the infection site. Moreover, they highlight a potential interest in mycolactone as a novel immunosuppressive agent.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
DCs survive exposure to mycolactone doses <50 ng/ml. (A and B) Induction of apoptosis in mouse bone marrow–derived DCs after exposure to mycolactone. The analysis was performed on CD11c+-gated cells incubated with mycolactone for 24 or 48 h concomitantly with 10 ng/ml LPS (iDCs) or after 24 h of stimulation with 10 ng/ml LPS (mDCs). (C and D) Induction of apoptosis in human peripheral blood–derived DCs incubated with mycolactone for 24 or 48 h concomitantly (iDCs) or after 48 h of stimulation with TNF-α/PGE2 (mDCs). Annexin V+/PI− cells were identified as early apoptotic cells, Annexin V+/PI+ cells were identified as late apoptotic cells, and Annexin V−/PI− cells were identified as live cells. Data are mean percentages and are representative of three independent experiments.
Figure 2.
Figure 2.
Mycolactone blocks DC maturation. (A) Representative histograms of CD83 and CD25 expression on human iDCs after stimulation by TNF-α/PGE2 in the presence of increasing doses of mycolactone for 48 h. (B) MFI of CD83 and CD25 expression on iDCs after stimulation by TNF-α/PGE2 for 48 h in the presence of mycolactone. Each line corresponds to one of the n donors.
Figure 3.
Figure 3.
Mycolactone inhibits functional maturation of DCs in vivo. (A) Mice were injected intradermally into the ear with TNF-α alone (−) or TNF-α + mycolactone (+). After 4 h, mice were killed. Ear explants were placed in an overnight culture, and the number of DCs in the crawl-out population was determined. Data are means and SD of CD11c+ PI− cell numbers from pooled skin explant cultures of two independent experiments. (B) Histograms of MHC class II and CD86 expression on DCs (CD11c+ PI−) from skin explant cultures of mice injected with TNF-α alone (white) or TNF-α + mycolactone (black). Data are representative of pooled skin explant cultures from two independent experiments.
Figure 4.
Figure 4.
Mycolactone reduces the allostimulatory capacity of human DCs. The proliferation of peripheral blood lymphocytes after incubation with allogeneic mycolactone-treated DCs is shown. DCs were matured in vitro with TNF-α/PGE2 in the presence of 0, 10, or 25 ng/ml mycolactone for 48 h and extensively washed before addition to the lymphocytes. T cell proliferation was measured after 6 d of co-culture. Data are means and SD of [3H]thymidine incorporation measured on triplicate wells and are representative of five independent experiments.
Figure 5.
Figure 5.
Mycolactone-treated DCs only moderately alter the expression of inflammatory cytokines by iDCs. (A) Concentration of IL-12 (p40 subunit) in culture supernatants from mouse iDCs stimulated with LPS in the presence of 0 or 50 ng/ml mycolactone for 48 h or left unstimulated (unstim). (C) IL-1α, IL-1β, and IL-6 mRNA expression is shown for mouse iDCs stimulated with LPS for 48 h in the presence of increasing doses of mycolactone. (B, D, and E) Production of IL-12 (p70), TNF-α, and IL-6 is shown for human peripheral blood–derived iDCs stimulated with LPS or poly I:C in the presence of increasing doses of mycolactone for 24 h. Data are means and SD and are representative of two independent experiments.
Figure 6.
Figure 6.
Mycolactone considerably affects the expression of inflammatory chemokines by iDCs. The expression of MIP-1α, MIP-1β, RANTES, IP-10, MCP-1, and IL-8 chemokines is shown for human monocyte-derived iDCs, or TNF-α/PGE2–matured mDCs, after stimulation with LPS or poly I:C in the presence of increasing doses of mycolactone for 24 h. Data are means and SD and are representative of two independent experiments.
Figure 7.
Figure 7.
Endogenous production of mycolactone blocks the expression of inflammatory chemokines by Mu-infected iDCs. The expression of MIP-1α, MIP-1β, and RANTES is shown for human monocyte-derived iDCs after infection with WT Mu or a mycolactone-deficient mutant (mup045), using an multiplicity of infection of 1:1 or 5:1 acid-fast bacilli/cell, in the presence of 10 μg/ml LPS. Controls include medium only, iDCs stimulated with LPS in the presence of 25 ng/ml mycolactone, and iDCs infected with mup045 in the presence of 25 ng/ml mycolactone. Data are means and SD and are representative of four independent experiments.

References

    1. Wansbrough-Jones, M., and R. Phillips. 2006. Buruli ulcer: emerging from obscurity. Lancet. 367:1849–1858. - PubMed
    1. George, K.M., D. Chatterjee, G. Gunawardana, D. Welty, J. Hayman, R. Lee, and P.L.C. Small. 1999. Mycolactone: a polyketide toxin from Mycobacterium ulcerans required for virulence. Science. 283:854–857. - PubMed
    1. Coutanceau, E., L. Marsollier, R. Brosch, E. Perret, P. Goossens, M. Tanguy, S.T. Cole, P.L.C. Small, and C. Demangel. 2005. Modulation of the host immune response by a transient intracellular stage of Mycobacterium ulcerans: the contribution of endogenous mycolactone toxin. Cell. Microbiol. 7:1187–1196. - PubMed
    1. Guarner, J., J. Bartlett, E.A.S. Whitney, P.L. Raghunathan, Y. Stienstra, K. Asamoa, S. Etuaful, E. Klutse, E. Quarshie, T.S. van der Werf, et al. 2003. Histopathologic features of Mycobacterium ulcerans infection. Emerg. Infect. Dis. 9:651–656. - PMC - PubMed
    1. Oliveira, M.S., A.G. Fraga, E. Torrado, A.G. Castro, J.P. Pereira, A.L. Filho, F. Milanezi, F.C. Schmitt, W.M. Meyers, F. Portaels, et al. 2005. Infection with Mycobacterium ulcerans induces persistent inflammatory responses in mice. Infect. Immun. 73:6299–6310. - PMC - PubMed

Publication types

Full text links
Silverchair Information Systems full text link Silverchair Information Systems Free PMC article
Cite

AltStyle によって変換されたページ (->オリジナル) /