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Paracoccidioidomycosis in silica-treated rats
Abstract:
An attempt is made to evaluate the importance of macrophages in the early local reaction to infection caused by the fungus Paracoccidioides brasiliensis. With this purpose, an attempt was made to impair macrophagic activity in the site of the fungal inoculum, by means of previous injections of silica. Twenty male rats were intraperitoneally infected with yeast cells of the fungus. Ten of the rats were injected intraperitoneally with silica particles twice, namely 24 and 4 h before the infection. All the animals were killed 4 wk after fungal inoculum. The results showed that the disease was aggravated in rats pre-treated with silica, clearly demonstrated by the 100% metastatic pulmonary involvement, in contrast with only 40% observed in the non-treated controls.
Insights
Silica treatment impaired macrophage activity, worsening Paracoccidioides brasiliensis infection in rats. This led to increased metastatic pulmonary involvement, highlighting macrophages
Area of Science:
- Mycology
- Immunology
- Infectious Diseases
Background:
- Paracoccidioides brasiliensis is a fungus causing paracoccidioidomycosis.
- Macrophages play a crucial role in the host's immune response to fungal infections.
Purpose of the Study:
- To evaluate the role of macrophages in the early local immune response to Paracoccidioides brasiliensis infection.
- To assess the impact of impaired macrophage activity on the progression of paracoccidioidomycosis.
Main Methods:
- Twenty male rats were used.
- Ten rats received intraperitoneal silica injections to impair macrophage activity 24 and 4 hours before infection.
- All rats were infected intraperitoneally with Paracoccidioides brasiliensis yeast cells and observed for 4 weeks.
Main Results:
- Silica pre-treatment aggravated the fungal infection in rats.
- 100% of silica-treated rats developed metastatic pulmonary involvement.
- Only 40% of non-treated control rats showed pulmonary involvement.
Conclusions:
- Macrophage activity is critical in controlling early Paracoccidioides brasiliensis infection.
- Impairing macrophage function exacerbates fungal dissemination and disease severity.
- Macrophages are essential for limiting the early local spread of Paracoccidioides brasiliensis.