Combination of Histopathology and FT-Raman Spectroscopy for the Study of Experimental Paracoccidioidomycosis in the Spleen.

Paracoccidioides brasiliensis (Pb) can disseminate through the lymphatic and hematogenic pathways. As a result the spleen and other lymphoid organs are targets of paracoccidioidomycosis. There are few studies describing this disease in the spleen and more detailed descriptions are required. This study combines Histopathology and Fourier Transform Raman Spectroscopy (FT-Raman) methods to study spleen infected by Pb. The Swiss mice were euthanized after 1, 2, 4 and 8 weeks of infection with Pb, and their spleens were removed for ex vivo analyzes. Histopathological evaluation revealed that the red pulp was the area most affected, presenting the highest concentration of yeasts, inflammatory cells and cells in apoptosis, with no observation of typical granuloma formation. The main physical-chemical changes were detected in the spectral ranges between 1730-1590 cm-1 and 1390-1280 cm-1 attributed to amide I and vibrational deformation mode of CH3 and CH2 molecules, respectively. The amide I was correlated to total protein content and CH3 and CH2 molecules to collagen of the spleen. The association between histological and physical-chemical methods enabled detection of several alterations in the spleen, including apoptosis, contributing to a better understanding of paracoccidioidomycosis, a tropical neglected disease.