Modulation of the immune response by Fonsecaea pedrosoi morphotypes in the course of experimental chromoblastomycosis and their role on inflammatory response chronicity

A common theme across multiple fungal pathogens is their ability to impair the establishment of a protective immune response. Although early inflammation is beneficial in containing the infection, an uncontrolled inflammatory response is detrimental and may eventually oppose disease eradication. Chromoblastomycosis (CBM), a cutaneous and subcutaneous mycosis, caused by dematiaceous fungi, is capable of inducing a chronic inflammatory response. Muriform cells, the parasitic form of Fonsecaea pedrosoi, are highly prevalent in infected tissues, especially in long-standing lesions. In this study we show that hyphae and muriform cells are able to establish a murine CBM with skin lesions and histopathological aspects similar to that found in humans, with muriform cells being the most persistent fungal form, whereas mice infected with conidia do not reach the chronic phase of the disease. Moreover, in injured tissue the presence of hyphae and especially muriform cells, but not conidia, is correlated with intense production of pro-inflammatory cytokines in vivo. Highthroughput RNA sequencing analysis (RNA-Seq) performed at early time points showed a strong up-regulation of genes related to fungal recognition, cell migration, inflammation, apoptosis and phagocytosis in macrophages exposed in vitro to muriform cells, but not conidia. We also demonstrate that only muriform cells required FcγR and Dectin-1 recognition to be internalized in vitro, and this is the main fungal form responsible for the intense inflammatory pattern observed in CBM, clarifying the chronic inflammatory reaction observed in most patients. Furthermore, our findings reveal two different fungal-host interaction strategies according to fungal morphotype, highlighting fungal dimorphism as an important key in understanding the bipolar nature of inflammatory response in fungal infections

Avaliação do tratamento da cromoblastomicose experimental utilizando vacina de DNA (DNA-hsp65)

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Medicina, 2010.A cromoblastomicose (CBM) é uma micose subcutânea, crônica, de distribuição cosmopolita, causada por vários fungos demáceos, pigmentados e dimórficos. Pacientes com a doença ainda são tidos como desafio terapêutico, principalmente devido à sua natureza recalcitrante. Várias são as opções envolvendo o tratamento dessa micose comumente negligenciada, contudo, ainda não há terapia de primeira escolha no combate à doença. O itraconazol e a terbinafina foram os que apresentaram os melhores resultados no tratamento da CBM, embora a cura de casos severos ainda seja rara. No entanto, vários trabalhos relatam as vacinas de DNA como promissoras no tratamento de infecções fúngicas, as quais permitem o restabelecimento da imunidade celular geralmente deprimida, minimizando os efeitos tóxicos oriundos das terapias antifúngicas convencionais. Nesse contexto, o presente trabalho foi conduzido, visando estabelecer inicialmente um modelo experimental confiável da CBM, propondo ainda novas terapêuticas para a doença, incluindo a utilização da vacina de DNA-hsp65. Por meio de análise morfomética, histopatológica e quantificação/recuperação das unidades formadoras de colônia, foi possível evidenciar o surgimento de lesões crônicas da CBM, embora transitórias, semelhantes às apresentadas em humanos. O esquema de tratamento empregando o itraconazol e a anfotericina B, intralesionalmente, mostrou-se eficaz no tratamento da CBM experimental, assim como a terapia utilizando a vacina de DNA-hsp65, livre. Foi demonstrado ainda, que a associação: quimioterápico + DNAhsp65 é eficiente no tratamento da CBM experimental, acelerando o processo de cura da doença, mitigando possíveis efeitos tóxicos advindos de quimioterapias prolongadas. _________________________________________________________________________________ ABSTRACTChromoblastomycosis (CBM) is a chronic worldwide subcutaneous mycosis, caused by several dimorphic, pigmented dematiaceous fungi. Patients with the disease are still considered as therapeutic challenge, mainly due to its recalcitrant nature. There is no treatment of choice for this neglected mycosis, but rather several treatment options. Itraconazole and terbinafine showed the best results in treating the disease, although the healing of severe cases is still uncommon. However, several studies have reported the DNA vaccine as promising in the treatment of fungal infections, which allow the host to restore depressed cellular immunity, minimizing the toxic effects from conventional antifungal therapies. In this matter, this work was conducted aiming the establishment of a suitable model for experimental CBM, suggesting also new therapies, including DNA-hsp65 vaccine. By analyzing the morfometrical and histopathological aspects, also the recovery/quantification of colony forming units, the results showed the establishment of a chronic, although transitory, experimental CBM model with lesions similar to that presented in humans. The treatment regimen using itraconazole and amphotericin B, intralesionally, was effective in treating experimental CBM, as well as therapy using naked DNA-hsp65 vaccine. It also has been shown that chemotherapy associated with DNA-hsp65 vaccine is efficient in the treatment of experimental CBM, accelerating the healing process of the disease, becoming able to tone down the toxic effects from prolonged chemotherapy

Imunopatologia da cromoblastomicose : modulação da resposta inflamatória por formas do fungo fonsecaea pedrosoi e seu impacto na cromoblastomicose murina

A cromoblastomicose (CBM) é uma micose subcutânea, crônica, de distribuição cosmopolita, causada por vários fungos demáceos, pigmentados e dimórficos. Pacientes com a doença ainda são tidos como desafio terapêutico, principalmente devido à sua natureza recalcitrante. Tendo em vista a persistência do fungo no tecido e a cronicidade das lesões, a ativação do sistema imunológico do hospedeiro apresenta grande relevância nessa micose. Após infecção com diferentes formas do fungo Fonsecaea pedrosoi (conídios, hifas e células muriformes) isoladamente foi observado manifestações distintas da CBM murina experimental de modo que infecção com células muriformes promoveu o estabelecimento de doença mais duradoura em comparação à infecção com as demais formas do fungo. Ademais, foi visto que a presença de hifas e, principalmente, de células muriformes na lesão, mas não de conídios, está relacionada com alta produção de citocinas pro-inflamatórias durante o estabelecimento da CBM experimental. Sequenciamento de alto desempenho do RNA (RNA-seq) de macrófagos recém-migrados para o peritônio em co-cultivo com conídios ou células muriformes do fungo mostraram que a interação com células muriformes, mas não com conídios, acarreta em intensa regulação positiva de genes relacionados com a resposta inflamatória do hospedeiro repercutindo em alta produção de citocinas pró-inflamatórias, de modo que o estabelecimento de inflamação exacerbada foi correlacionado com a persistência do fungo na lesão. Mecanismos efetores e a expressão de genes importantes na ativação da resposta imune adaptativa estão inibidos na interação com as formas do fungo. Análise das subpopulações de linfócitos T no linfonodo drenante e no sítio de infecção no curso da CBM murina experimental por citometria de fluxo mostraram polarização de linfócitos T com perfil regulatório no linfonodo poplíteo ao passo que no coxim plantar foi observada a predominância de Th17 nos estágios iniciais da doença, sendo sucedida por uma polarização Th1 nos estágios mais tardios, relacionados com a remissão da doença. Ensaios in vivo de neutralização de IL-17A e IFN-γ obstaram o processo de eliminação do fungo no curso da doença. De modo semelhante, animais dectina-2 KO, os quais apresentaram redução na população de Th17 no curso da doença, mostrou redução da carga fúngica prejudicada nos primeiros 15 dias de infecção sem, contudo, afetar a resolução da doença. Por fim, depleção in vivo de células CD25+, a qual leva à redução de células Treg presentes no linfodo drenante, repercutiu em maior redução da carga fúngica nos primeiros 15 dias de infecção, todavia se opos ao processo de remissão da doença observada no modelo experimental murino. Assim, de modo geral, o presente trabalho traz novos elementos na compreensão da imunopatologia da doença, de forma que trabalhos futuros envolvendo a imunomodulação da resposta do hospedeiro para aquela mais efetiva pode representar uma estratégia promissora no tratamento, não só da CBM, como das demais micoses. _________________________________________________________________________________________________ ABSTRACTChromoblastomycosis (CBM) is a chronic worldwide subcutaneous mycosis, caused by several dimorphic, pigmented dematiaceous fungi. Patients with the disease are still considered as therapeutic challenge, mainly because of its recalcitrant nature. Due to fungal persistence in the tissue and lesions chronicity, the immune system activation in the host is highly relevant in this mycosis. After infection with different Fonsecaea pedrosoi fungal forms alone (conidia, hyphae and muriform cells), it was observed distinct manifestations of experimental murine CBM so that infection with muriformes cells promoted the establishment of longer lasting disease compared to infection with other fungal forms. Moreover, the presence of hyphae and especially muriformes cells in skin lesions, but no conidia, is related with high production of pro-inflammatory cytokines during the establishment of experimental CBM. High throughput RNA sequencing (RNA-seq) of Thioglycollate-elicited peritoneal macrophages co-cultivated with conidia or muriformes fungal cells showed that the interaction with muriformes cells, but not with conidia, results in strong upregulation of genes related to inflammatory response leading to a high production of proinflammatory cytokines, while exacerbated inflammation was correlated with the persistence of the fungus on the lesion. Effector mechanisms and the expression of genes important to adaptive immune response activation are inhibited in the interaction with the fungal cells. Analysis of T lymphocyte subpopulations in draining lymph node and in the site of infection during the course of experimental CBM by flow cytometry showed polarization of T lymphocytes with regulatory status in the popliteal lymph node while in the footpad was observed predominance of Th17 in the early stages of disease, being succeeded by Th1 popularization in the later stages, which is associated with disease remission. In vivo analysis with IL-17A and IFN-γ neutralization hindered fungal cell elimination in the course of the disease. Similarly, dectin-2 KO animals, Th17 contraction in the course of the disease showed fungal burden impairment in the first 15 days of infection, but did not affected the disease resolution. Finally, in vivo depletion of CD25+ cells, which leads to reduction of Treg cells in the draining lymph node, reflected in greater reduction in fungal burden in the first 15 days of infection, however it opposes to disease remission observed in the experimental CBM. Thus, in general, this study brings new elements in the understanding of the immunopathology of CBM, so that future work involving immunomodulation of the host response to a more effective pattern can represent a promising strategy for the treatment, not only of CBM, but to other mycoses as well

Early immune response against Fonsecaea pedrosoi requires Dectin-2-mediated Th17 activity, whereas Th1 response, aided by Treg cells, is crucial for fungal clearance in later stage of experimental chromoblastomycosis.

Chromoblastomycosis (CBM) is a chronic worldwide subcutaneous mycosis, caused by several dimorphic, pigmented dematiaceous fungi. It is difficult to treat patients with the disease, mainly because of its recalcitrant nature. The correct activation of host immune response is critical to avoid fungal persistence in the tissue and disease chronification. CD4+ T cells are crucial for the development of protective immunity to F. pedrosoi infection. Here, we investigated T helper cell response dynamics during experimental CBM. Following footpad injection with F. pedrosoi hyphae and conidia, T cells were skewed towards a Th17 and Th1 phenotype. The Th17 population was the main Th cell subset found in the infected area during the early stages of experimental murine CBM, followed by Th1 predominance in the later stages, coinciding with the remission phase of the disease in this experimental model. Depletion of CD25+ cells, which leads to a reduction of Treg cells in the draining lymph node, resulted in decline in fungal burden after 14 days of infection. However, fungal cells were not cleared in the later stages of the disease, prolonging CBM clinical features in those animals. IL-17A and IFN-γ neutralization hindered fungal cell elimination in the course of the disease. Similarly, in dectin-2 KO animals, Th17 contraction in the course of experimental CBM was accompanied by fungal burden decrease in the first 14 days of infection, although it did not affect disease resolution. In this study, we gained insight into T helper subsets' dynamics following footpad injections of F. pedrosoi propagules and uncovered their contribution to disease resolution. The Th17 population proved to be important in eliminating fungal cells in the early stages of infection. The Th1 population, in turn, closely assisted by Treg cells, proved to be relevant not only in the elimination of fungal cells at the beginning of infection but also essential for their complete elimination in later stages of the disease in a mouse experimental model of CBM

The Major Chromoblastomycosis Etiologic Agent Fonsecaea pedrosoi Activates the NLRP3 Inflammasome

Fonsecaea pedrosoi is the main etiologic agent of chromoblastomycosis (CBM), one of the most prevalent subcutaneous mycosis in tropical and subtropical countries. CBM is a poorly characterized chronic infection that commonly starts after transcutaneous inoculation of conidia and saprophytic hyphae of F. pedrosoi. Recently, we have shown that unlike conidia, hyphae and muriform cells (the parasitic morphotype) of F. pedrosoi promotes an intense inflammatory response pattern in vivo, which comprises the production of an inflammasome-derived cytokine, IL-1β. Nonetheless, the mechanisms underlying IL-1β production and maturation upon F. pedrosoi infection and its functional output in the course of CBM remains unknown. We show here that F. pedrosoi hyphae, differently from conidia, induce IL-1β secretion in both bone marrow-derived dendritic cells and macrophages. Using inhibitors and knockout cells, we demonstrated that the mechanisms underlying IL-1β production by hyphae-infected macrophages were dependent on dectin-1, -2, and -3 receptors and the Syk-NF-kB signaling pathway. Furthermore, F. pedrosoi promoted a NLRP3-dependent inflammasome activation, which required potassium efflux, reactive oxygen species production, phagolysosomal acidification, and cathepsin B release as triggers. IL-1β processing and release was mediated primarily by caspase-1 and, to a lesser extent, by caspase-8-dependent cleavage. Finally, we showed using a murine CBM model that F. pedrosoi elicits a NLRP3-regulated IL-1β and interleukin-18 release in vivo, but without NLRP3 inflammasome activation interfering in the course of the experimental infection