Fibrotic sequelae in pulmonary paracoccidioidomycosis: histopathological aspects in BALB/c mice infected with viable and non-viable Paracoccidioides brasiliensis propagules

Authors

  • Ana M. COCK Clínica de las Vegas; Laboratorio de Patología
  • Luz E. CANO Corporación para Investigaciones Biológicas
  • Diana VÉLEZ Corporación para Investigaciones Biológicas
  • Beatriz H. ARISTIZÁBAL Corporación para Investigaciones Biológicas
  • Judith TRUJILLO Universidad Pontificia Bolivariana; Facultad de Medicina
  • Angela RESTREPO Corporación para Investigaciones Biológicas

Keywords:

Pulmonary fibro, Paracoccidioides brasilien, Viable coni, Fragmented yeast ce, Histopathol, Collagen fib, Granuloma format

Abstract

Patients with paracoccidioidomycosis often present pulmonary fibrosis and exhibit important respiratory limitations. Based on an already established animal model, the contribution of viable and non-viable P. brasiliensis propagules to the development of fibrosis was investigated. BALB/c male mice, 4-6 weeks old were inoculated intranasally either with 4x10(6 )viable conidia (Group I), or 6.5x10(6) fragmented yeast cells (Group II). Control animals received PBS. Six mice per period were sacrificed at 24, 48, 72h (initial) and 1, 2, 4, 8, 12 and 16 weeks post-challenge (late). Paraffin embedded lungs were sectioned and stained with H&E, trichromic (Masson), reticulin and Grocott´s. During the initial period PMNs influx was important in both groups and acute inflammation involving 34% to 45% of the lungs was noticed. Later on, mononuclear cells predominated. In group I, the inflammation progressed and granulomas were formed and by the 12th week they fussed and became loose. Thick collagen I fibers were observed in 66.6% and 83.3% of the animals at 8 and 12 weeks, respectively. Collagen III, thick fibers became apparent in some animals at 4weeks and by 12 weeks, 83% of them exhibited alterations in the organization and thickness of these elements. In group II mice, this pattern was different with stepwise decrease in the number of inflammatory foci and lack of granulomas. Although initially most animals in this group had minor alterations in thin collagen I fibers, they disappeared by the 4th week. Results indicate that tissue response to fragmented yeast cells was transitory while viable conidia evoked a progressive inflammatory reaction leading to granuloma formation and to excess production and/or disarrangement of collagens I and III; the latter led to fibrosis.

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Published

2000-04-01

Issue

Section

Mycology

How to Cite

COCK, A. M., CANO, L. E., VÉLEZ, D., ARISTIZÁBAL, B. H., TRUJILLO, J., & RESTREPO, A. (2000). Fibrotic sequelae in pulmonary paracoccidioidomycosis: histopathological aspects in BALB/c mice infected with viable and non-viable Paracoccidioides brasiliensis propagules . Revista Do Instituto De Medicina Tropical De São Paulo, 42(2), 59-66. https://revistas.usp.br/rimtsp/article/view/30410