Adult BALB/c mice of both sexes were infected intranasally with 10(6) viable P. brasiliensis conidia. Animals were sacrificed at intervals up to 6 months and studied by histopathology and organ cultures. At the time of challenge lung sections showed that instilled conidia had reached the alveoli; at 12 h such conidia were transforming into yeast cells, with multiple buds appearing by 18 h. Initially, the cellular infiltrate was composed of polymorphonuclear leukocytes; 6 days later, lymphocytes, plasmocytes and macrophages predominated. Multinucleated giant cells appeared only after 6 weeks. The rate of pulmonary infection as determined by organ culture was high (82 of the 83 mice studied). The experimental infection was progressive as indicated by increasing numbers of viable fungi with time. The results of this study demonstrate that the conidia produced by P. brasiliensis mycelial form are infectious, producing active disease in healthy animals.

Experimental murine paracoccidiodomycosis induced by the inhalation of conidia

The effect of coculturing yeast-form Paracoccidioides brasiliensis with murine cells was studied. Coculture of resident peritoneal or pulmonary macrophages with P. brasiliensis for 72 h dramatically enhanced fungal multiplication 19.3 +/- 2.4- and 4.7 +/- 0.8-fold, respectively, compared with cocultures with lymph node cells or complete tissue culture medium alone. Support of P. brasiliensis multiplication by resident peritoneal macrophages was macrophage dose dependent. Lysates of macrophages, supernatants from macrophage cultures, or McVeigh-Morton broth, like complete tissue culture medium, did not support multiplication of P. brasiliensis in 72-h cultures. Time course microscopic studies of cocultures in slide wells showed that macrophages ingested P. brasiliensis cells and that the ingested cells multiplied intracellularly. In sharp contrast to resident macrophages, lymphokine-activated peritoneal and pulmonary macrophages not only prevented multiplication but reduced inoculum CFU by 96 and 100%, respectively, in 72 h. Microscopic studies confirmed killing and digestion of P. brasiliensis ingested by activated macrophages in 48 h. These findings indicate that resident macrophages are permissive for intracellular multiplication of P. brasiliensis and that this could be a factor in pathogenicity. By contrast, activated macrophages are fungicidal for P. brasiliensis.

Intracellular multiplication of Paracoccidioides brasiliensis in macrophages: killing and restriction of multiplication by activated macrophages.

Paracoccidioidomycosis, one of the most important endemic and systemic mycoses in Latin America, presents several clinical pictures. Epidemiological studies indicate a striking rarity of disease (but not infection) in females, but only during the reproductive years. This suggested a hormonal interaction between female hormones and the etiologic dimorphic fungus Paracoccidioides brasiliensis. Many fungi have been shown to use hormonal (pheromonal) fungal molecules for intercellular communication, and there are increasing numbers of examples of interactions between mammalian hormones and fungi, including the specific binding of mammalian hormones by fungal proteins, and suggestions of mammalian hormonal modulation of fungal behavior. This suggests an evolutionary conservation of hormonal receptor systems. We recount studies showing the specific hormonal binding of mammalian estrogen to proteins in P. brasiliensis and an action of estrogen to specifically block the transition from the saprophytic form to the invasive form of the fungus in vitro. This block has been demonstrated to occur in vivo in animal studies. These unique observations are consistent with an estrogen-fungus receptor-mediated effect on pathogenesis. The fungal genes responsive to estrogen action are under study.

Hormones and the Resistance of Women to Paracoccidioidomycosis

Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, a systemic mycosis endemic to Latin America. In this paper we review clinical, therapeutic and immunological aspects of the disease, as well as the biology and ecology of the fungus, restricting the review to the period 1989-1992.

Paracoccidioidomycosis and its etiologic agent Paracoccidioides brasiliensis

The dissemination of Paracoccidioides brasiliensis cells to the heart, omentum/pancreas, spleen, liver and lungs, assessed by colony forming unit (CFU) counts, the levels of specific antibodies to this fungal agent (by ELISA), and the specific DTH reaction were studied in susceptible (B10.A) and resistant (A/Sn) mice. The animals were infected intraperitoneally with P. brasiliensis yeast cells and were evaluated 2, 4, 12 and 16 weeks later. The most remarkable differences between the two mouse strains were observed 16 weeks after infection, when B10.A mice displayed high numbers of CFU in all examined organs, except the heart, high antibody titres, and depressed DTH response. At this point, A/Sn mice presented low or absent CFU in all organs, low antibody titres and expressive DTH response. The CFU counts were shown to be a reliable parameter to discriminate susceptible from resistant animals. The fungal load in the most affected organs correlated with the antibody titres and was inversely correlated with the intensity of the DTH reaction. The patterns of immune response in this model mimic human paracoccidioidomycosis, in which high specific antibody levels and depressed DTH reactions are found in multifocal and severe forms of the disease.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2249.1993.tb05980.x

Experimental murine paracoccidioidomycosis: relationship among the dissemination of the infection, humoral and cellular immune responses

The present paper describes a murine model for pulmonary paracoccidioidomycosis injecting 6×105 yeast forms ofParacoccidioides brasiliensis (Pb) by the direct intratracheal route. The sequential histopathology of lung and dissemination lesions together with humoral (immunodiffusion test) and cellular immune response (footpad test and macrophage inhibition factor assay — MIF assay) were investigated since the 1st to the 360th day after infection. All infected animal showed pulmonary Pbmycosis up to Day 30; onwards the lesions subsided being found only in one mouse at Day 360. Dissemination lesions were observed in paratracheal and cervical lymph nodes in 9 out of 68 infected animals. Histologically early lesions were rich in polymorphonuclear cells and evolved to a macrophage desquamative pneumonitis at Day 15 and to typical epithelioid granulomata from Day 30 up to Day 360. Specific precipitating antibodies were first detected 15 days after infection, peaked from Day 30 to 60 and were not observed at Day 360. Significant cell-mediated immunity to Pb was noted at Day 15 with the peak reaction at Day 60 and 90.

Experimental pulmonary paracoccidioidomycosis in mice: morphology and correlation of lesions with humoral and cellular immune response.

https://www.hillpublisher.com/ArticleDetails.aspx?type=PDF&cid=1334

M. F. de Franco

Papers

Experimental pulmonary paracoccidioidomycosis in mice: morphology and correlation of lesions with humoral and cellular immune response.

Relationship between Arterial Calcification and Fetuin-A Levels in Patients with Chronic Kidney Disease at the Onset of Hemodialysis