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A remarkable aspect of the human fungal pathogen Cryptococcus neoformans is the morphological changes triggered by the interaction with the host. During infection, a specific morphological change in cell size is observed, particularly in lung tissue, from regular 5 to 7 µm cells (RCs) to titan cells (TCs, > 10 µm and up to 100 µm). However, the stable and reproducible generation of large quantity of TCs was only possible during experimental infection. We implemented here in vitro conditions allowing TCs generation with the aim to understand the ancestry of TC, the environmental determinants of TCs formation and perform easily phenotype/genotype analysis to uncover genetic factors underlying TCs formation. This paper reports robust in vitro conditions that generates yeasts cells harboring the main characteristics of TCs: large (>10 µm), uninucleate and polyploid cells harboring a single large vacuole with a dense capsule surrounding a thickened melanized cell wall. We observed that TCs formation begins as soon as 8 hours after induction, with a maximal proportion of TCs obtained after 24 hours. TCs derived for the initial oldest cells (mother cells) rather than from daughter cells. Hypoxia, nutrient starvation and low pH stresses were the main factors that trigger TCs formation, while quorum sensing factors like the initial inoculum concentration and the addition of pantothenic acid also impacted TCs formation. Antifungal drugs, resulting in inhibition of ergosterol (fluconazole), or proteins and nucleic acids (flucytosine), altered TCs formation, as did hosts-related products such as serum, phospholipids and anti-capsular antibodies in our settings. We then explored genetic factors important for TCs formation using two approaches. Using strains from H99 lineage strains among which few genetic differences have been described, we showed that TCs formation was dependent on Lmp1, Sgf29 and Gpr4/5-Rim101 proteins. Then, based on a the analysis of natural Pkr1 loss-of-function clinical isolates and serial clinical isolates, we observed the important role of Pkr1 protein, a negative regulator of the cyclic adenosine monophosphate / protein kinase A (cAMP/PKA), for TCs formation. These strains also emphasize the structural and functional relationship between Pkr1 and Pka. Our results provide new insights into TCs biogenesis with identification of multiple important factors/pathways involved. The implementation of such standardized and robust in vitro conditions pave the way for future research focusing on the genetic basis of TCs biogenesis, biology of TCs and the ontology of morphological changes in Cryptococcus neoformans. Author Summary Cryptococcus neoformans is a yeast that is capable of morphological change upon interaction with host. Particularly, in the lung of infected mice, a subpopulation of yeast evolves toward gigantism (titan cells size from 10 to 100 µm) that include other characteristics such as thickened cell wall, dense capsule, polyploidization, large vacuole with peripheral nucleus and cellular organelles. The generation of large number of such cells outside the lung of mice have been described but was not reproducible nor standardized. We here report standardized, reproducible, robust conditions of generation of titan cells and explored the environmental and genetic factors underlying the genesis of these cells. We showed that Titan cells were generated upon stresses such as change in the medium, nutrient deprivation, hypoxia and low pH. Using collection of well characterized reference strains and clinical isolates, we validated with our model the AMPc/PKA/Rim pathway as the major genetic determinant of titan cell formation. This study opens the way for a more comprehensive picture of the ontology of morphological changes in Cryptococcus neoformans.

International audience; Toll-like receptors are key to pathogen recognition by a host and to the subsequent triggering of an innate immune response. Experimental and clinical evidence shows that defects in Toll-like receptors or in signaling pathways downstream from these receptors render hosts susceptible to various types of infection, including aspergillosis. Patients receiving an immunosuppressive regimen, including corticosteroid therapy or cytotoxic chemotherapy, are also susceptible to infections. Aspergillus fumigatus is an opportunistic pathogen that infects the lungs of immunosuppressed hosts. Here, we review the evidence that experimental inactivation of various Toll-like receptors and of their signaling pathways may worsen cases of invasive pulmonary aspergillosis. Moreover, the literature clearly indicates that the type of immunosuppression is very important, as it influences whether or not Toll-like receptors contribute to infection. The involvement of Toll-like receptors, based on the immunological status of the patient, should be considered if an immunosuppressive treatment must be administered.

International audience; This article examined neural time course differences in the processing of emotional pictures in European and Asian individuals. Event-related potentials (ERPs) were recorded in 15 French and 15 Japanese volunteers during the presentation of neutral and emotional pictures in their own country. ERPs were analyzed by means of spatio-temporal Principal Component Analysis (PCA) and allow to evaluate cultural influences on emotional processing along three temporal windows: 105 to 140 ms, 176 to 230 ms and 255 to 455 ms. Main results highlight that (1) early ERP components coded emotional charge but were not modulated by cultural background, (2) later components showed a significant decrease of amplitudes at parieto-occipital areas for Japanese participants compared to French ones in emotional condition. These findings suggest that, in both populations, similar neurocognitive processes are involved in the early stage of the emotional stimuli processing and effects observed on later components may reflect a poorer engagement of parietal areas, known to be involved in emotional arousal dimension. Considering that cognitive judgments were similar in both populations, electrophysiological findings suggest that cultural influences on later stage of emotional processing could be related to the known lower level of emotionally expressive behavior in Japanese than in Caucasians.

International audience; INTRODUCTION: Diffuse fibrosing sarcoidosis represents an important predisposing factor for infection by Aspergillus sp. The clinical features and specific complications are illustrated by 3 case reports. BACKGROUND: Patients with chronic fibrosing sarcoidosis and cystic changes or cavitation in the upper lobes are the most prone to aspergillosis. Aspergilloma is the most common form and can be difficult to distinguish from chronic necrotising aspergillosis. Sarcoidosis with aspergillosis is associated with an increased incidence of respiratory failure and fatal haemoptysis. The 3 cases presented in this paper also illustrate the poor efficacy of oral antifungal drugs and bronchial embolisation. Surgery is often necessary but may be difficult on account of the extent of the lesions and poor respiratory function. VIEWPOINT: In the future the use of new drugs such as voriconazole and posaconazole may improve the prognosis of this complication. CONCLUSION: Aspergillosis represents a frequent complication of diffuse fibrosing sarcoidosis which warrants early detection and treatment on account of its poor prognosis.

International audience; We reviewed the records of 85 patients infected with both human immunodeficiency virus and Cryptococcus neoformans. Twenty-seven patients (32%) had pulmonary cryptococcosis. C. neoformans was cultured from bronchoalveolar lavage (BAL) or pleural fluid in 25 cases; the remaining two patients had cryptococcal antigen (CA) detected in BAL fluid and C. neoformans cultured from other sites. All but one of the 27 patients had detectable CA in serum. The CD4+ lymphocyte count was low in all cases (median, 24/mm3). Clinical manifestations of pulmonary cryptococcosis included fever (94%), cough (71%), dyspnea (7%), expectoration (4%), chest pain (2%), and hemoptysis (1%). Diffuse interstitial opacities (70.5%), focal interstitial abnormalities, alveolar opacities, adenopathies, cavitary lesions, and pleural effusions were evident. Outcome was poor (mean survival time, 23 weeks) despite treatment. Patients with localized pulmonary cryptococcosis appeared to have a higher CD4+ lymphocyte count, an earlier diagnosis, lower serum CA titers, fewer previous or concomitant infections, and a better prognosis than patients with disseminated cryptococcosis.