Journal
EUROPEAN JOURNAL OF IMMUNOLOGY
Volume 38, Issue 2, Pages 459-469Publisher
WILEY
DOI: 10.1002/eji.200737268
Keywords
bacterial infection; human; Tregs
Categories
Funding
- NIAID NIH HHS [AI 054629, R01 AI063514, R01 AI054629-01A2, AI 063514, R01 AI054629, R01 AI063514-01A1] Funding Source: Medline
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We evaluated the role of regulatory T cells (CD4(+) CD25(+) Foxp3(+) cells, Tregs) inhuman Mycobacterium tuberculosis infection. Tregs were expanded in response to M. tuberculosis in healthy tuberculin reactors, but not in tuberculin-negative individuals. The M. tuberculosis mannose-capped lipoarabinomannan (ManLAM) resulted in regulatory T cell expansion, whereas the M. tuberculosis 19-kDa protein and heat shock protein 65 had no effect. Anti-IL-10 and anti-TGF-beta alone or in combination, did not reduce expansion of Tregs. In contrast, the cyclooxygenase enzyme-2 inhibitor NS398 significantly inhibited expansion of Tregs, indicating that prostaglandin E2 (PGE2) contributes to Treg expansion. Monocytes produced PGE2 upon culturing with heat-killed M. tuberculosis or ManLAM, and T cells from healthy tuberculin reactors enhanced PGE2 production by monocytes. Expanded Tregs produced significant amounts of TGF-beta and IL-10 and depletion of Tregs from PBMC of these individuals increased the frequency of M. tuberculosis-responsive CD4(+) IFN-gamma cells. Culturing M. tuberculosis -expanded Tregs with autologous CD8(+) cells decreased the frequency of IFN-gamma(+) cells. Freshly isolated PBMC from tuberculosis patients had increased percentages of Tregs, compared to healthy tuberculin reactors. These findings demonstrate that Tregs expand in response to M. tuberculosis through mechanisms that depend on ManLAM and PGE2.
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