Regulatory T cell activity is partly inhibited in a mouse model of chronic Pseudomonas aeruginosa lung infection.

Abstract

OBJECTIVES:

We aimed to investigate the activity of regulatory T (Treg) cells in chronic Pseudomonas aeruginosa (PA) lung infection and its influence on effector T-cell responses.

MATERIALS AND METHODS:

C57BL/6 mice were randomly inoculated with PA-laden agarose beads (1 × 10(5) CFU/50 μL) or planktonic PA (1 × 10(5) CFU/50 μL), and euthanized at the time points of 4 hour, day 1, 3, 5, and 7. Bacterial load, bronchoalveolar lavage (BAL) fluid cell counts, and lung tissue histology were assessed. BAL fluid concentrations of TGF-β1, IFN-γ, IL-1β, IL-4, IL-6, IL-10, and IL-17A were measured. Messenger RNA (mRNA) levels of TGF-β1, IL-10 and CD4(+) T-cell subtype-specific transcription factors were determined. The expression of CD4(+)CD25(+)forkhead box P3 (FoxP3)(+) cells in lungs and spleens were analyzed.

RESULTS:

Mice inoculated with PA-laden agarose beads developed chronic PA lung infection during 7-day study period, while mice inoculated with planktonic PA cleared bacteria in 3 days. Compared with mice recovered from acute PA lung infection, those with chronic infection had significantly increased effector T-cell responses, accompanied by a more severe neutrophilic inflammation. Mice with chronic PA lung infection had significantly lower concentration of TGF-β1 and higher concentrations of IFN-γ, IL-1β, IL-6, and IL-17A in BAL fluid. Meanwhile, they had significantly lower mRNA levels of TGF-β1, IL-10 and FoxP3 in lung tissues, and lower expression of CD4(+)CD25(+)FoxP3(+) cells in lungs and spleens.

CONCLUSIONS:

These findings indicate that Treg cell activity is partly inhibited in mice with chronic PA lung infection, which contributes to the enhanced effector T-cell responses in airways.

• Authors: Feng-Ming Ding, Song-Lei Zhu, Ce Shen, Xiao-Li Ji, Xin Zhou
• Journal: Experimental lung research (Exp Lung Res) Vol. 41 Issue 1 Pg. 44-55 (Feb 2015) ISSN: 1521-0499 [Electronic] England
• PMID: 25398094 (Publication Type: Journal Article)

Chemical References

• Cytokines
• Forkhead Transcription Factors
• Foxp3 protein, mouse
• Tgfb1 protein, mouse
• Transforming Growth Factor beta1
• Interleukin-10

Topics

• Animals
• Chronic Disease
• Cytokines (metabolism)
• Disease Models, Animal
• Female
• Forkhead Transcription Factors (metabolism)
• Interleukin-10 (metabolism)
• Mice, Inbred C57BL
• Pneumonia, Bacterial (immunology, metabolism, microbiology)
• Pseudomonas Infections (immunology, metabolism, microbiology)
• Pseudomonas aeruginosa
• Random Allocation
• T-Lymphocytes, Helper-Inducer (metabolism)
• T-Lymphocytes, Regulatory (physiology)
• Transforming Growth Factor beta1 (metabolism)