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Depletion of Neutrophils Exacerbates the Early Inflammatory Immune Response in Lungs of Mice Infected with Paracoccidioides brasiliensis

View Article: PubMed Central - PubMed

ABSTRACT

Neutrophils predominate during the acute phase of the Paracoccidioides brasiliensis infection. Herein, we determined the role of the neutrophil during the early stages of experimental pulmonary paracoccidioidomycosis using a monoclonal antibody (mAb) specific for neutrophils. Male BALB/c mice were inoculated intranasally with 1.5 × 106 or 2 × 106 P. brasiliensis yeast cells. The mAb was administered 24 h before infection, followed by doses every 48 h until mice were sacrificed. Survival time was evaluated and mice were sacrificed at 48 h and 96 h after inoculation to assess cellularity, fungal load, cytokine/chemokine levels, and histopathological analysis. Neutrophils from mAb-treated mice were efficiently depleted (99.04%). Eighty percent of the mice treated with the mAb and infected with 1.5 × 106 yeast cells died during the first two weeks after infection. When mice were treated and infected with 2 × 106 yeast cells, 100% of them succumbed by the first week after infection. During the acute inflammatory response significant increases in numbers of eosinophils, fungal load and levels of proinflammatory cytokines/chemokines were observed in the mAb-treated mice. We also confirmed that neutrophils are an important source of IFN-γ and IL-17. These results indicate that neutrophils are essential for protection as well as being important for regulating the early inflammatory immune response in experimental pulmonary paracoccidioidomycosis.

No MeSH data available.


Related in: MedlinePlus

Depletion of neutrophils is associated with an exacerbated inflammatory response in lungs of mice infected with P. brasiliensis during the acute phase. The microphotographs shown are representative of lungs from mice infected or noninfected and treated or not with the anti-Ly6G specific mAb against neutrophils at 96 h after challenge and obtained from 4-5 mice/group. Lungs were fixed, embedded in paraffin, cut, and stained using H&E staining (a–g) to determine lung inflammatory response and methenamine silver staining (h–n) to identify P. brasiliensis yeast cells as described in the Materials and Methods section. Arrowheads indicate P. brasiliensis yeast cells (in brown). These results are representative of two independent experiments. (a) and (h) Control mice (inoculated with PBS); (b), (e), (i), and (l) infected, untreated mice; (c), (f), (j), and (m) infected mice treated with isotype control Ab; (d), (g), (k), and (n) infected mice treated with anti-Ly6G mAb. Magnification 40x (a–d, h–k) and 400x (e–g, l–o).
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fig2: Depletion of neutrophils is associated with an exacerbated inflammatory response in lungs of mice infected with P. brasiliensis during the acute phase. The microphotographs shown are representative of lungs from mice infected or noninfected and treated or not with the anti-Ly6G specific mAb against neutrophils at 96 h after challenge and obtained from 4-5 mice/group. Lungs were fixed, embedded in paraffin, cut, and stained using H&E staining (a–g) to determine lung inflammatory response and methenamine silver staining (h–n) to identify P. brasiliensis yeast cells as described in the Materials and Methods section. Arrowheads indicate P. brasiliensis yeast cells (in brown). These results are representative of two independent experiments. (a) and (h) Control mice (inoculated with PBS); (b), (e), (i), and (l) infected, untreated mice; (c), (f), (j), and (m) infected mice treated with isotype control Ab; (d), (g), (k), and (n) infected mice treated with anti-Ly6G mAb. Magnification 40x (a–d, h–k) and 400x (e–g, l–o).

Mentions: In order to investigate whether the decreased survival of infected and neutrophil-depleted mice was due to increased fungal load, we quantified fungal CFU obtained from lungs of mice at 48 and 96 h after infection with 1.5 × 106 P. brasiliensis yeast cells. Neutrophil-depleted mice showed a significant increase in the pulmonary fungal burden compared to untreated and isotype control-treated infected mice (Figure 1(d)). These findings are consistent with the histopathological analysis which confirmed the increased pulmonary fungal burden as demonstrated by an increment of P. brasiliensis yeast cells in the lungs of neutrophil-depleted infected mice at the acute phase of infection (Figures 2(k) and 2(n)) compared to untreated and isotype control-treated infected mice (Figures 2(i), 2(j), 2(l), and 2(m)).


Depletion of Neutrophils Exacerbates the Early Inflammatory Immune Response in Lungs of Mice Infected with Paracoccidioides brasiliensis
Depletion of neutrophils is associated with an exacerbated inflammatory response in lungs of mice infected with P. brasiliensis during the acute phase. The microphotographs shown are representative of lungs from mice infected or noninfected and treated or not with the anti-Ly6G specific mAb against neutrophils at 96 h after challenge and obtained from 4-5 mice/group. Lungs were fixed, embedded in paraffin, cut, and stained using H&E staining (a–g) to determine lung inflammatory response and methenamine silver staining (h–n) to identify P. brasiliensis yeast cells as described in the Materials and Methods section. Arrowheads indicate P. brasiliensis yeast cells (in brown). These results are representative of two independent experiments. (a) and (h) Control mice (inoculated with PBS); (b), (e), (i), and (l) infected, untreated mice; (c), (f), (j), and (m) infected mice treated with isotype control Ab; (d), (g), (k), and (n) infected mice treated with anti-Ly6G mAb. Magnification 40x (a–d, h–k) and 400x (e–g, l–o).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5015031&req=5

fig2: Depletion of neutrophils is associated with an exacerbated inflammatory response in lungs of mice infected with P. brasiliensis during the acute phase. The microphotographs shown are representative of lungs from mice infected or noninfected and treated or not with the anti-Ly6G specific mAb against neutrophils at 96 h after challenge and obtained from 4-5 mice/group. Lungs were fixed, embedded in paraffin, cut, and stained using H&E staining (a–g) to determine lung inflammatory response and methenamine silver staining (h–n) to identify P. brasiliensis yeast cells as described in the Materials and Methods section. Arrowheads indicate P. brasiliensis yeast cells (in brown). These results are representative of two independent experiments. (a) and (h) Control mice (inoculated with PBS); (b), (e), (i), and (l) infected, untreated mice; (c), (f), (j), and (m) infected mice treated with isotype control Ab; (d), (g), (k), and (n) infected mice treated with anti-Ly6G mAb. Magnification 40x (a–d, h–k) and 400x (e–g, l–o).
Mentions: In order to investigate whether the decreased survival of infected and neutrophil-depleted mice was due to increased fungal load, we quantified fungal CFU obtained from lungs of mice at 48 and 96 h after infection with 1.5 × 106 P. brasiliensis yeast cells. Neutrophil-depleted mice showed a significant increase in the pulmonary fungal burden compared to untreated and isotype control-treated infected mice (Figure 1(d)). These findings are consistent with the histopathological analysis which confirmed the increased pulmonary fungal burden as demonstrated by an increment of P. brasiliensis yeast cells in the lungs of neutrophil-depleted infected mice at the acute phase of infection (Figures 2(k) and 2(n)) compared to untreated and isotype control-treated infected mice (Figures 2(i), 2(j), 2(l), and 2(m)).

View Article: PubMed Central - PubMed

ABSTRACT

Neutrophils predominate during the acute phase of the Paracoccidioides brasiliensis infection. Herein, we determined the role of the neutrophil during the early stages of experimental pulmonary paracoccidioidomycosis using a monoclonal antibody (mAb) specific for neutrophils. Male BALB/c mice were inoculated intranasally with 1.5 × 106 or 2 × 106 P. brasiliensis yeast cells. The mAb was administered 24 h before infection, followed by doses every 48 h until mice were sacrificed. Survival time was evaluated and mice were sacrificed at 48 h and 96 h after inoculation to assess cellularity, fungal load, cytokine/chemokine levels, and histopathological analysis. Neutrophils from mAb-treated mice were efficiently depleted (99.04%). Eighty percent of the mice treated with the mAb and infected with 1.5 × 106 yeast cells died during the first two weeks after infection. When mice were treated and infected with 2 × 106 yeast cells, 100% of them succumbed by the first week after infection. During the acute inflammatory response significant increases in numbers of eosinophils, fungal load and levels of proinflammatory cytokines/chemokines were observed in the mAb-treated mice. We also confirmed that neutrophils are an important source of IFN-γ and IL-17. These results indicate that neutrophils are essential for protection as well as being important for regulating the early inflammatory immune response in experimental pulmonary paracoccidioidomycosis.

No MeSH data available.


Related in: MedlinePlus