Mycoses d'importation: le point sur la paracoccidioïdomycose

Neutrophil Extracellular Traps Identification in Tegumentary Lesions of Patients with Paracoccidioidomycosis and Different Patterns of NETs Generation In Vitro

Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in most Latin American countries, especially in Brazil. It is caused by the thermo-dimorphic fungus of the genus Paracoccidioides (Paracoccidioides brasiliensis and Paracoccidioides lutzii). Innate immune response plays a crucial role in host defense against fungal infections, and neutrophils (PMNs) are able to combat microorganisms with three different mechanisms: phagocytosis, secretion of granular proteins, which have antimicrobial properties, and the most recent described mechanism called NETosis. This new process is characterized by the release of net-like structures called Neutrophil Extracellular Traps (NETs), which is composed of nuclear (decondensed DNA and histones) and granular material such as elastase. Several microorganisms have the ability of inducing NETs formation, including gram-positive and gram-negative bacteria, viruses and some fungi. We proposed to identify NETs in tegumentary lesions of patients with PCM and to analyze the interaction between two strains of P. brasiliensis and human PMNs by NETs formation in vitro. In this context, the presence of NETs in vivo was evidenced in tegumentary lesions of patients with PCM by confocal spectrum analyzer. Furthermore, we showed that the high virulent P. brasiliensis strain 18 (Pb18) and the lower virulent strain Pb265 are able to induce different patterns of NETs formation in vitro. The quantification of extracellular DNA corroborates the idea of the ability of P. brasiliensis in inducing NETs release. In conclusion, our data show for the first time the identification of NETs in lesions of patients with PCM and demonstrate distinct patterns of NETs in cultures challenged with fungi in vitro. The presence of NETs components both in vivo and in vitro open new possibilities for the detailed investigation of immunity in PCM.

Paracoccidioidomycosis (PCM) is an infectious disease caused by fungi of genus Paracoccidioides (P. brasiliensis and P. lutzii). PCM is endemic in Latin America, with a greater incidence in Brazil, Colombia, and Argentina. Over the last years, studies are focusing on neutrophils’ (PMNs) actions against P. brasiliensis, due to the capacity of these cells to develop different defense strategies against pathogens. and especially due to constant presence of inflammatory infiltrates full of PMNs in the granuloma of the disease. As PMN release of both granular and nuclear material, identified as Neutrophil Extracellular Traps (NETs), is a spectacular action mechanism against microbes, we seek to identify whether this process would be an important mechanism triggered against P. brasiliensis. Thus, we showed for the first time the identification of NETs in tegumentary lesions of patients with PCM by viewing the individual components of NETs. Beyond that, we demonstrated the entrapment of P. brasiliensis in vitro by these structures released from human PMNs of patients with PCM and healthy donors, with different patterns, in a dependence of the evaluated strain. Our data provides important new information regarding the role of PMNs against P. brasiliensis, opening new avenues for the research on immunity of PCM.

IL-18 triggered by the Nlrp3 inflammasome induces host innate resistance in a pulmonary model of fungal infection

Pathogens are sensed by innate immune receptors that initiate an efficient adaptive immune response upon activation. The elements of the innate immune recognition process for Paracoccidioides brasiliensis include TLR-2, TLR-4, and dectin-1. However, there are additional receptors necessary for the host immune responses to P. brasiliensis. The nucleotide-binding oligomerization domain-like receptor (NLRs), which activate inflammasomes, are candidate receptors that deserve renewed investigation. After pathogen infection, the NLRs form large signaling platforms called inflammasomes, which lead to caspase-1 activation and maturation of proinflammatory cytokines (IL-18 and IL-1β). In this study, we showed that NLR family pyrin domain-containing 3 (Nlrp3) is required to induce caspase-1 activation and further secretion of IL-1β and IL-18 by P. brasiliensis-infected macrophages. Additionally, potassium efflux and lysosomal acidification induced by the fungus were important steps in the caspase-1 activation mechanism. Notably, Nlrp3 and caspase-1 knockout mice were more susceptible to infection than were the wild-type animals, suggesting that the Nlrp3-dependent inflammasomes contribute to host protection against P. brasiliensis. This protective effect occurred owing to the inflammatory response mediated by IL-18, as shown by an augmented fungus burden in IL-18 knockout mice. Taken together, our results show that the Nlrp3 inflammasome is essential for resistance against P. brasiliensis because it orchestrates robust caspase-1 activation and triggers an IL-18-dependent proinflammatory response.

Paracoccidioidomycosis in southern Rio Grande do Sul: a retrospective study of histopathologically diagnosed cases

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by the fungus Paracoccidioides brasiliensis and is endemic to Brazil. The aim of this study was to perform a retrospective analysis of the PCM cases in the countryside south of Rio Grande do Sul, Brazil. The files from four histopathology laboratories located in the city of Pelotas were obtained, and all of the epidemiological and clinical data from the PCM diagnosed cases were collected for analysis. A total of 123 PCM cases diagnosed between 1966 and 2009 were selected. Of these patients, 104 (84.5%) were male, and 17 were female. The patients ranged from 02 to 92 years of age. Fifty-two cases (41.9%) were obtained from the oral pathology laboratory, and the remaining 71 cases (58.1%) were obtained from the three general pathology laboratories. Of all of the patients studied, 65.2% lived in rural zones and worked in agriculture or other related fields. Data on the evolution of this disease was available for 43 cases, and the time frame ranged from 20 to 2920 days (mean = 572.3 days). An accurate diagnosis performed in less than 30 days only occurred in 21% of the cases. PCM is endemic to the countryside of Rio Grande do Sul. Therefore, it is recommended that PCM be included as a differential diagnosis, mainly for individuals between 30 and 60 years of age, living in rural zones and who have respiratory signs and associated-oropharyngeal lesions.

5-Lipoxygenase activity increases susceptibility to experimental Paracoccidioides brasiliensis infection

Paracoccidioidomycosis (PCM) is a systemic mycosis caused by the thermodimorphic fungus Paracoccidioides brasiliensis. Leukotrienes and lipoxins are lipid mediators produced after 5-lipoxygenase (5-LO) activation that exhibit pro- and anti-inflammatory roles, respectively. Here, we have investigated the contribution of 5-LO enzymatic activity in PCM using an experimental model of P. brasiliensis infection. B6.129 wild-type (B6.129) and 5-LO-deficient (5-LO(-/-)) mice were intravenously inoculated with a virulent strain of P. brasiliensis (Pb18), and the survival rate of the infected mice was investigated on different days after yeast infection. 5-LO(-/-) mice exhibited an increased survival rate associated with a decreased number of CFU. The resistance of 5-LO(-/-) during PCM was associated with augmented nitric oxide (NO) production and the formation of compact granulomas. In addition, the absence of 5-LO was associated with a diminished number of CD4(+) CD25(+) regulatory T cells, higher levels of gamma interferon and interleukin-12, and increased T-bet (a T-box transcription factor that directs Th1 lineage commitment) mRNA levels in the lungs. Taken together, our results show for the first time that 5-LO enzymatic activity increases susceptibility to P. brasiliensis, suggesting that this pathway may be a potential target for therapeutic intervention during PCM.

Retinal involvement of Paracoccioidomycosis: A Case Report

Purpose: to describe the clinicopathologic features and treatment of a rare case of systemic paracoccidioidomycosis with choroidal and retinal involvement. Design: retrospective interventional case report. Participant: A 36-year-old young man with visual impairment in left eye with anterior uveitis and presence of whitish perimacular choroidal nodule, multiple underlying whitish spots and mid-periphery exudative retinal detachment. A primary extensive work-up for systemic infectious, autoimmune, neoplasic or inflammatory conditions was performed and high-resolution computer tomography scan demonstrated asymmetric parietal thickening of the trachea and bilateral diffuse multiple lobular opacities. Pulmonary bronchoscopy/biopsy of larynx, trachea and bronchial tube were also performed. Histopathological evaluation showed characteristic of Paracoccidioidomycosis. Intervention: Patient was treated with oral sulphadiazine (1.5 g/day). Main Outcome Measures: Anterior uveitis, retinal examination, histopathological evaluation and primary clinical outcome were observed during systemic treatment. Results: After 3 months of irregular treatment, choroidal lesions decreased in size forming atrophic scars and fibrotic spots; however visual acuity did not show any improvement. Conclusion: We report a rare case of systemic paracoccidioidomycosis with choroidal and retinal involvement treated with oral sulphadiazine.

Important aspects of oral paracoccidioidomycosis--a literature review

Paracoccidioidomycosis is a deep mycosis endemic to Latin America, with considerable morbidity and mortality. It is caused by the dimorphic fungus Paracoccidioides brasiliensis, which affects, among other organs in the human body, the oral cavity. Fungus virulence and immunocompetence of the host determine the establishment of infection or active disease, whose severity and clinical behaviour depend mostly on the cellular immune response of the host. Often, oral lesions constitute the first sign and site of confirmation of diagnosis, which in most cases is delayed. The success of the treatment depends on early and correct diagnosis, as well as on the patient's adherence to the drug therapy.