Jorge Lobo's disease: experimental inoculation in Swiss mice

Lobomycosis. Literature review and future perspectives

Lobomycosis is a cutaneous infection of tropical and subtropical regions caused by the fungus Lacazia loboi, which still has a controversial taxonomical position. The first description of the disease and fungus was made in 1930 by Jorge Lobo. It is a chronic disease with predominance of lesions similar to keloids, in exposed areas, limited to skin and semimucosa. There is no systemic involvement and patients maintain a good general health. Diagnosis is confirmed by direct or histopathologic exam and, until present, the fungus has not been cultivated. Surgery is the treatment of choice for isolated lesions, but there are frequent recurrences. Good therapeutic responses have been reported with clofazimine, with or without itraconazole, and with 5-fluorocytosine. This disease should be recognized by dermatologists worldwide because, although restricted to the Amazon region, it has been observed in other locations. Research development and achievement of new knowledge in molecular biology and genetic engineering of lobomycosis are of utmost importance because they may, in the future, lead to the culture of the fungus in the laboratory and to a better understanding of its pathogenesis, transmission mechanism, and new methods of diagnosis, prevention and treatment.

Is TGF-beta important for the evolution of subcutaneuos chronic mycoses?

Jorge Lobo's and chromoblastomycosis are chronic deep mycosis that clinically manifests as keloid and verrucous polymorphic lesions of solid consistency and variable size that contain small scales and crusts. Few studies are available in the literature characterizing the in situ cellular and humoral immune response, especially the involvement of cytokines which immunosuppressive and fibrogenic effects as the TGF-beta. The hypothesis of the present paper is explaining the possible mechanism of this cytokine in cutaneous lesions pathology in chromoblastomycosis and lacaziosis (Jorge Lobo's disease). The results of this investigation are a new hypothesis for ethiopatogenesis of these diseases: TGF-beta is a double effect that follows fibrosis and immunosuppression in local skin.

Macrophage and TGF-beta immunohistochemical expression in Jorge Lobo's disease

Jorge Lobo's disease, or lacaziosis, is a chronic deep mycosis that clinically manifests as solid, variable-sized nodular parakeloidal lesions. Few studies have characterized the in situ cellular and humoral immune response, especially the involvement of cytokines with immunosuppressive effects such as TGF-beta. The objective this paper was to analyze the expression of TGF-beta in cutaneous lesions in lacaziosis and investigate its importance in the etiopathogy of the disease. The results indicate that the abundance of collagen bands, together with weak immunolabeling for CD68 seen in macrophages, indicates a concomitant effect of TGF-beta inhibiting macrophages and inducing fibrosis, which is responsible for the keloid aspect frequently acquired by these lesions. Finally, the evolution of the infection supports the hypothesis that TGF-beta plays a fundamental role in the etiopathology of Lacazia loboi infection, either by inhibiting the cellular immune response mainly mediated by macrophages or by inducing fibrosis. Further studies are necessary to better characterize the phenotype of the inflammatory infiltrate as well as the participation of other cytokines and growth factors in the tissue response of the host in Jorge Lobo's disease.

Lacaziose (doença de Jorge Lobo): revisão e atualização

Lacaziose ou doença de Jorge Lobo é micose crônica, granulomatosa, causada por implantação traumática do fungo Lacazia loboi - patógeno não cultivável até o presente - nos tecidos cutâneo e subcutâneo, manifestando-se clinicamente por lesões nodulares queloidianas predominantes, envolvendo sobretudo pavilhões auriculares, face, membros superiores e inferiores, e não comprometendo as mucosas. A maioria dos casos humanos está registrada em países da América do Sul. Entretanto, a enfermidade apresenta aspectos epidemiológicos destacados, como o aparecimento em tribo Caiabi, no Brasil Central e em mamíferos não humanos, golfinhos de duas espécies (Tursiops truncatus e Sotalia guianensis) capturados na costa da Flórida (EUA), na foz do rio Suriname, na costa de Santa Catarina (Brasil), no golfo de Gasconha (baía de Biscaia-Europa), com manifestações cutâneas e achados histopatológicos muito similares às encontradas no homem. O artigo objetiva abordar características do fungo e sua taxonomia, e aspectos históricos, ecoepidemiológicos, clínicos, imuno-histoquímicos, histopatológicos, ultra-estruturais e terapêuticos.

Molecular model for studying the uncultivated fungal pathogen Lacazia loboi

Lacazia loboi is an uncultivated fungal pathogen of humans and dolphins that causes cutaneous and subcutaneous infections only in the tropical areas of the Americas. It was recently found by phylogenetic analysis that this unusual pathogen is closely related to Paracoccidioides brasiliensis and to the other fungal dimorphic members of the order Onygenales. That original phylogenetic study used universal primers to amplify well-known genes. However, this approach cannot be applied to the study of other proteins. We have developed a strategy for studying the gene encoding the gp43 homologous protein of P. brasiliensis in L. loboi. The gp43 protein was selected because it has been found that this P. brasiliensis antigen strongly reacts when it is used to test sera from patients with lacaziosis. The principle behind this idea was to obtain the gp43 amino acid sequence of P. brasiliensis and other homologous fungal sequences from GenBank and design primers from their aligned conserved regions. These sets of primers were used to amplify the selected regions with genomic DNA extracted from the yeast-like cells of L. loboi from experimentally infected mice. Using this approach, we amplified 483 bp of the L. loboi gp43-like gene. These sequences had 85% identity at the nucleotide level and 75% identity with the deduced amino acid sequences of the P. brasiliensis gp43 protein. The identity of the 483-bp DNA fragment was confirmed by phylogenetic analysis. This analysis revealed that the L. loboi gp43-like deduced amino acid sequence formed a strongly supported (100%) sister group with several P. brasiliensis gp43 sequences and that this taxon in turn was linked to the other fungal sequences used in this analysis. This study shows that the use of a molecular model for investigation of the genes encoding important proteins in L. loboi is feasible.

Experimental reproduction of the Jorge Lobo's disease in BAlb/c mice inoculated with Lacazia loboi obtained from a previously infected mouse

Long-term maintenance of Lacazia loboi in the laboratory has not been reported. We report here the use BALB/c mice to maintain the Lacazia loboi for extended period of time. Eight to ten week-old mice were inoculated intradermally in both hind footpads with a fungal suspension from a macerated footpad obtained from an original mouse previously infected with the fungi and sacrificed 8 months after inoculation. The inoculated animals were sacrificed at different time intervals, footpads were excised, the right one was submitted to histopathological examination and the left one was macerated in sterile saline for fungal count and viability index determination. The inoculated animals presented the histopathological picture identical to the mice previously inoculated with material from human lesion. Granulomatous infiltrates with predominance of macrophages and giant cells were observed. The granulomas evolved progressively as observed in the different times of sacrifice. After 7 months of inoculation, macroscopic lesions were observed, and the number of fungi obtained from macerated footpads was higher than the number of inoculated fungi. The pattern of lesion development was similar to what was observed in animals infected with a fungal suspension obtained from a human lesion. Considering the histopathological findings, the clinical manifestations, and the finding of a higher number of fungi obtained than the inoculated into footpads of each mice, we believe the BALB/c mice strain is as an excellent way to maintain L. loboi in laboratory. Moreover, even after serial passages of the fungi, the granulomatous lesions are reproduced consistently in laboratory conditions.