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Loss- and Gain-of-Function Approaches Indicate a Dual Role Exerted by Regulatory T Cells in Pulmonary Paracoccidioidomycosis.

Bazan SB, Costa TA, de Araújo EF, Feriotti C, Loures FV, Pretel FD, Calich VL - PLoS Negl Trop Dis (2015)

Bottom Line: Although regulatory T (Treg) cells were shown to control immunity against PCM, deleterious or protective effects were described in different experimental settings.Depletion of Treg cells led to reduced fungal load, diminished pathogen dissemination and increased Th1/Th2/Th17 immunity.Nevertheless, transfer of Treg cells combined with CD4+Foxp3- T cells generated more efficient and balanced immune Th1/Th2/Th17 responses able to limit pathogen growth and excessive tissue inflammation, leading to regressive disease and increased survival rates.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.

ABSTRACT
Paracoccidioidomycosis (PCM), is a pulmonary fungal disease whose severity depends on the adequate development of T cell immunity. Although regulatory T (Treg) cells were shown to control immunity against PCM, deleterious or protective effects were described in different experimental settings. To clarify the function of Treg cells in pulmonary PCM, loss-and gain-of-function approaches were performed with Foxp3GFP knock-in mice and immunodeficient Rag1-/- mice, respectively, which were intratracheally infected with 106 yeast cells. The activity of Foxp3-expressing Treg cells in pulmonary PCM was determined in Foxp3GFP transgenic mice. First, it was verified that natural Treg cells migrate to the lungs of infected mice, where they become activated. Depletion of Treg cells led to reduced fungal load, diminished pathogen dissemination and increased Th1/Th2/Th17 immunity. Further, adoptive transfer of diverse T cell subsets to Rag1-/- mice subsequently infected by the pulmonary route demonstrated that isolated CD4+Foxp3+ Treg cells were able to confer some degree of immunoprotection and that CD4+Foxp3- T cells alone reduced fungal growth and enhanced T cell immunity, but induced vigorous inflammatory reactions in the lungs. Nevertheless, transfer of Treg cells combined with CD4+Foxp3- T cells generated more efficient and balanced immune Th1/Th2/Th17 responses able to limit pathogen growth and excessive tissue inflammation, leading to regressive disease and increased survival rates. Altogether, these loss- and gain-of-function approaches allow us to clearly demonstrate the dual role of Treg cells in pulmonary PCM, their deleterious effects by impairing T cell immunity and pathogen eradication, and their protective role by suppressing exacerbated tissue inflammation.

No MeSH data available.


Related in: MedlinePlus

In the absence of Tregs, mice show exacerbated inflammatory responses.(A) Photomicrographs of lungs, livers and spleens from Rag1-/- mice infected with Pb18 after adoptive cell transfer of Treg, CD4+Foxp3- T cells and Treg + CD4+Foxp3- T cells. Organ sections were stained with H&E and Grocott and examined under a light microscope with a magnification of 100×. Morphometric analysis of lesions in lungs, livers and spleens from Rag1-/- mice after 6 weeks of infection with Pb18. (B) Areas of lesions were quantified from photomicrographs of organ sections. Data represent the mean ± SD from three experiments (n ≥ 5; *p < 0.05; ** p < 0.005; ***p < 0.001; ND = not detectable).
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pntd.0004189.g007: In the absence of Tregs, mice show exacerbated inflammatory responses.(A) Photomicrographs of lungs, livers and spleens from Rag1-/- mice infected with Pb18 after adoptive cell transfer of Treg, CD4+Foxp3- T cells and Treg + CD4+Foxp3- T cells. Organ sections were stained with H&E and Grocott and examined under a light microscope with a magnification of 100×. Morphometric analysis of lesions in lungs, livers and spleens from Rag1-/- mice after 6 weeks of infection with Pb18. (B) Areas of lesions were quantified from photomicrographs of organ sections. Data represent the mean ± SD from three experiments (n ≥ 5; *p < 0.05; ** p < 0.005; ***p < 0.001; ND = not detectable).

Mentions: Disease severity was also evaluated in organ sections from all groups of mice after 2 and 6 weeks of infection. At week 2 post-infection, lungs of mice receiving either vehicle or Treg cells showed yeasts-containing granulomas and substantial destruction of the lung architecture (Fig 7A). By contrast, mice reconstituted with CD4+Foxp3- T cells or CD4+Foxp3- T cells + Treg cells exhibited diffuse inflammation in the lung tissue, containing disperse or no yeast cells. After 6 weeks of infection, lungs of mice receiving vehicle or Treg showed a vast number of granulomas containing a high number of fungal particles compromising a large area of pulmonary tissue (Fig 7A). Lungs of mice reconstituted with CD4+Foxp3- T cells still showed intense and disseminated cellular infiltration in the alveolar spaces and in the peribronchiolar and perivascular regions, but with few detectable yeast cells. Lungs of mice given CD4+Foxp3- T cells + Treg cells showed signs of resolved inflammation and low number of fungal particles. Livers from mice receiving vehicle or Treg cells showed a great number of granulomas containing yeast cells, whereas livers from mice reconstituted with CD4+Foxp3- T cells or CD4+Foxp3- T cells + Treg cells displayed preserved tissue architecture (Fig 7A).


Loss- and Gain-of-Function Approaches Indicate a Dual Role Exerted by Regulatory T Cells in Pulmonary Paracoccidioidomycosis.

Bazan SB, Costa TA, de Araújo EF, Feriotti C, Loures FV, Pretel FD, Calich VL - PLoS Negl Trop Dis (2015)

In the absence of Tregs, mice show exacerbated inflammatory responses.(A) Photomicrographs of lungs, livers and spleens from Rag1-/- mice infected with Pb18 after adoptive cell transfer of Treg, CD4+Foxp3- T cells and Treg + CD4+Foxp3- T cells. Organ sections were stained with H&E and Grocott and examined under a light microscope with a magnification of 100×. Morphometric analysis of lesions in lungs, livers and spleens from Rag1-/- mice after 6 weeks of infection with Pb18. (B) Areas of lesions were quantified from photomicrographs of organ sections. Data represent the mean ± SD from three experiments (n ≥ 5; *p < 0.05; ** p < 0.005; ***p < 0.001; ND = not detectable).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4626087&req=5

pntd.0004189.g007: In the absence of Tregs, mice show exacerbated inflammatory responses.(A) Photomicrographs of lungs, livers and spleens from Rag1-/- mice infected with Pb18 after adoptive cell transfer of Treg, CD4+Foxp3- T cells and Treg + CD4+Foxp3- T cells. Organ sections were stained with H&E and Grocott and examined under a light microscope with a magnification of 100×. Morphometric analysis of lesions in lungs, livers and spleens from Rag1-/- mice after 6 weeks of infection with Pb18. (B) Areas of lesions were quantified from photomicrographs of organ sections. Data represent the mean ± SD from three experiments (n ≥ 5; *p < 0.05; ** p < 0.005; ***p < 0.001; ND = not detectable).
Mentions: Disease severity was also evaluated in organ sections from all groups of mice after 2 and 6 weeks of infection. At week 2 post-infection, lungs of mice receiving either vehicle or Treg cells showed yeasts-containing granulomas and substantial destruction of the lung architecture (Fig 7A). By contrast, mice reconstituted with CD4+Foxp3- T cells or CD4+Foxp3- T cells + Treg cells exhibited diffuse inflammation in the lung tissue, containing disperse or no yeast cells. After 6 weeks of infection, lungs of mice receiving vehicle or Treg showed a vast number of granulomas containing a high number of fungal particles compromising a large area of pulmonary tissue (Fig 7A). Lungs of mice reconstituted with CD4+Foxp3- T cells still showed intense and disseminated cellular infiltration in the alveolar spaces and in the peribronchiolar and perivascular regions, but with few detectable yeast cells. Lungs of mice given CD4+Foxp3- T cells + Treg cells showed signs of resolved inflammation and low number of fungal particles. Livers from mice receiving vehicle or Treg cells showed a great number of granulomas containing yeast cells, whereas livers from mice reconstituted with CD4+Foxp3- T cells or CD4+Foxp3- T cells + Treg cells displayed preserved tissue architecture (Fig 7A).

Bottom Line: Although regulatory T (Treg) cells were shown to control immunity against PCM, deleterious or protective effects were described in different experimental settings.Depletion of Treg cells led to reduced fungal load, diminished pathogen dissemination and increased Th1/Th2/Th17 immunity.Nevertheless, transfer of Treg cells combined with CD4+Foxp3- T cells generated more efficient and balanced immune Th1/Th2/Th17 responses able to limit pathogen growth and excessive tissue inflammation, leading to regressive disease and increased survival rates.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.

ABSTRACT
Paracoccidioidomycosis (PCM), is a pulmonary fungal disease whose severity depends on the adequate development of T cell immunity. Although regulatory T (Treg) cells were shown to control immunity against PCM, deleterious or protective effects were described in different experimental settings. To clarify the function of Treg cells in pulmonary PCM, loss-and gain-of-function approaches were performed with Foxp3GFP knock-in mice and immunodeficient Rag1-/- mice, respectively, which were intratracheally infected with 106 yeast cells. The activity of Foxp3-expressing Treg cells in pulmonary PCM was determined in Foxp3GFP transgenic mice. First, it was verified that natural Treg cells migrate to the lungs of infected mice, where they become activated. Depletion of Treg cells led to reduced fungal load, diminished pathogen dissemination and increased Th1/Th2/Th17 immunity. Further, adoptive transfer of diverse T cell subsets to Rag1-/- mice subsequently infected by the pulmonary route demonstrated that isolated CD4+Foxp3+ Treg cells were able to confer some degree of immunoprotection and that CD4+Foxp3- T cells alone reduced fungal growth and enhanced T cell immunity, but induced vigorous inflammatory reactions in the lungs. Nevertheless, transfer of Treg cells combined with CD4+Foxp3- T cells generated more efficient and balanced immune Th1/Th2/Th17 responses able to limit pathogen growth and excessive tissue inflammation, leading to regressive disease and increased survival rates. Altogether, these loss- and gain-of-function approaches allow us to clearly demonstrate the dual role of Treg cells in pulmonary PCM, their deleterious effects by impairing T cell immunity and pathogen eradication, and their protective role by suppressing exacerbated tissue inflammation.

No MeSH data available.


Related in: MedlinePlus