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Experimental paracoccidioidomycosis in hamster: transmission electron microscopy of inoculation site lesion
K I Coelho1, K Takeo, M Yamaguchi
1Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan.
Abstract:
Interaction between Paracoccidioides brasiliensis (Pb) and inflammatory cells in hamster testis was studied sequentially by transmission electron microscopy. In early lesions (six hours after inoculation), polymorphonuclear neutrophils (PMNs) were the major and mononuclear cells and eosinophils were the minor constituents of the inflammatory cells. PMNs were later replaced by mononuclear cells. Viable Pb cells were phagocytosed or surrounded by inflammatory cells. Preserved Pb cells usually had broad host-parasite interphases, whereas dying ones had narrow interphases. The outer layer of the fungus wall was sometimes broken by PMN in some focal points, broken pieces being peeled off and phagocytosed. Small Pb cells were uninuclear, and were often related to broad interphase. Large Pb cells were multinucleated with irregularly shaped wall, and sometimes had lomasome and/or myelin like structures. Different interaction patterns of Pb with inflammatory cells may be due to functionally different host cell flow to the inoculation site or due to the age of Pb cells or both.
Insights
This study observed how Paracoccidioides brasiliensis (Pb) interacts with hamster immune cells in testes. Polymorphonuclear neutrophils initially attack Pb, later replaced by mononuclear cells, influencing fungal survival.
Area of Science:
- Mycology
- Immunology
- Pathology
Background:
- Paracoccidioides brasiliensis (Pb) is a fungus causing paracoccidioidomycosis.
- The interaction between Pb and host inflammatory cells is crucial for disease progression.
- Understanding these interactions in specific tissues like the testis is important.
Purpose of the Study:
- To sequentially investigate the interaction between Paracoccidioides brasiliensis and inflammatory cells in hamster testis.
- To characterize the morphological changes in both fungal and host cells during infection.
Main Methods:
- Transmission electron microscopy was used for sequential observation.
- Hamster testis tissue was analyzed at early stages (six hours post-inoculation).
- Identification and characterization of inflammatory cell types and their interaction with Pb.
Main Results:
- Early lesions showed polymorphonuclear neutrophils (PMNs) as the primary inflammatory cells, later replaced by mononuclear cells.
- Viable Pb cells were phagocytosed or surrounded by inflammatory cells, with preserved cells showing broad host-parasite interphases.
- Fungal cell wall integrity was affected by PMNs, and morphological differences were observed between small (uninuclear) and large (multinuclear) Pb cells.
Conclusions:
- The dynamic interaction involves sequential infiltration and replacement of inflammatory cells.
- Host-parasite interphase width correlates with Pb viability.
- Variations in Pb morphology and interaction patterns may depend on host cell influx and fungal age.