Polysaccharides Cell Wall Architecture of Mucorales

Invasive fungal infections are some of the most life-threatening infectious diseases in the hospital setting. In industrialized countries, the most common fungal species isolated from immunocompromised patients are Candida and Aspergillus spp. However, the number of infections due to Mucorales spp. is constantly increasing and little is known about the virulence factors of these fungi. The fungal cell wall is an important structure protecting fungi from the environment. A better knowledge of its composition should improve our understanding of host-pathogen interactions. Cell wall molecules are involved in tissue adherence, immune escape strategies, and stimulation of host defenses including phagocytosis and mediators of humoral immunity. The fungal cell wall is also a target of choice for the development of diagnostic or therapeutic tools. The present review discusses our current knowledge on the cell wall structure of Mucorales in terms of the polysaccharides and glyco-enzymes involved in its biosynthesis and degradation, with an emphasis on the missing gaps in our knowledge

Chronic Mucocutaneous Candidiasis in Autoimmune Polyendocrine Syndrome Type 1

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is an autosomal recessive disease caused by mutations in the autoimmune regulator (AIRE) gene, characterized by the clinical triad of chronic mucocutaneous candidiasis (CMC), hypoparathyroidism, and adrenal insufficiency. CMC can be complicated by systemic candidiasis or oral squamous cell carcinoma (SCC), and may lead to death. The role of chronic Candida infection in the etiopathogenesis of oral SCC is unclear. Long-term use of fluconazole has led to the emergence of Candida albicans strains with decreased susceptibility to azoles. CMC is associated with an impaired Th17 cell response; however, it remains unclear whether decreased serum IL-17 and IL-22 levels are related to a defect in cytokine production or to neutralizing autoantibodies resulting from mutations in the AIRE gene

Mycobiome and inflammatory bowel diseases : Impact of dysbiosis on intestinal inflammation and the fibrotic process

Introduction. Alors que le mycobiote représente une part quantitative négligeable, en apparence, du microbiote intestinal, les preuves de son rôle dans les maladies inflammatoires chroniques de l’intestin, et notamment la maladie de Crohn (MC), sont croissantes. Ce travail avait pour objectif d’évaluer l’impact de Candida albicans et Saccharomyces cerevisiae sur l’inflammation et la fibrose intestinale (FI), mais également sur la production des anticorps anti-S. cerevisiae (ASCA), reconnaissant des séquences oligomannosidiques de faible degré de polymérisation ayant un résidu α,1-3 mannose terminal.Méthodes. Des modèles murins (C57BL/6, axénique et CEABAC10 exprimant CEACAM6 humaine) et cellulaires (fibroblaste CCD-18Co et cellule épithéliale intestinale Caco-2) d’inflammation et de FI induites (par sulfate de dextrane sodique ou TGF-β) ont été utilisés pour évaluer les réponses cellulaires, tissulaires et systémiques aux levures et à la souche bactérienne LF82, souche adhérente invasive d’Escherichia coli (AIEC) utilisée comme témoin, par analyse histologique, RT-q-PCR et détermination des ASCA. Parallèlement, une analyse métagénomique (MTG) du mycobiote fécal et la détermination des ASCA et de la calprotectine fécale étaient réalisés dans le cadre d’une étude cas-témoins, « MAGIC », incluant des sujets atteints de la MC de diagnostic récent et en rémission clinique comparés à leurs apparentés sains du premier degré, ainsi qu’à des témoins sains appariés. Cette étude était réalisée en collaboration avec d’autres équipes de recherche, analysant notamment le microbiote fécal bactérien et caractérisant les souches AIEC.Résultats. Dans le modèle murin de FI chimio-induite, LF82 aggravait l’inflammation et la FI cliniquement, microscopiquement et à l’échelle de l’expression génique (EG). C. albicans augmentait l’EG surtout des marqueurs de l’inflammation alors que S. cerevisiae n’avait pas d’effet. In vitro, seules les cellules épithéliales répondaient au TGF-β et/ou à LF82 et l’EG des marqueurs pro-fibrotiques était augmentée, tandis que les levures n’avaient pas d’effet sur la FI. Par ailleurs, les levures n’induisaient pas la synthèse d’ASCA chez les différents modèles murins étudiés. Dans l’étude clinique MAGIC, 41,7% des patients atteints de la MC étaient porteurs d’ASCA, 2,9% des apparentés sains et 1,8% des témoins sains, aucune différence n’était observée selon l’âge. L’analyse MTG bactérienne, montrait un profil spécifique chez les apparentés sains (richesse et AIEC plus élevées) vs. témoins et patients atteints de MC, liée notamment à la présence de bactéries symbiontes, mais également la présence plus élevée d’AIEC vs. témoins ; les patients atteints de MC présentaient une diversité plus basse vs. témoins et apparentés sains, ainsi que la présence d’AIEC plus élevée vs. témoins. Cependant, le mycobiote fécal était similaire entre les différents groupes, que ce soit en abondance relative (notamment pour C. albicans et S. cerevisiae), ou en alpha-, beta-diversités. Aucune association n’a été retrouvée entre micromycètes et les différents paramètres évalués (calprotectine, ASCA, AIEC).Conclusion. Dans les limites des modèles utilisés, les levures ici étudiées n’avaient pas d’impact sur la FI, contrairement à LF82, et ne semblaient pas être responsables de la synthèse d’ASCA. L’hypothèse de l’auto-anticorps reste à approfondir. L’analyse MTG fongique des selles des sujets de l’étude MAGIC fait suggérer que les modifications observées dans d’autres études seraient une conséquence de la MC. En effet, l’absence de profil fongique spécifique pourraient s’expliquer par le fait que les sujets inclus atteints de MC présentaient un diagnostic récent et donc un profil fongique peu modifié à ce stade de la maladie. Toutefois, la qualité de ces données justifie que ces résultats soient confirmés sur une large cohorte de patients atteints de MC suivis de manière séquentielle en début et au décours de la maladie.Introduction. While the mycobiota represents a seemingly negligible quantitative proportion of the intestinal microbiota, evidence of its role in chronic inflammatory bowel diseases, and in particular in Crohn's disease (CD), is growing. This work aimed to evaluate the impact of Candida albicans and Saccharomyces cerevisiae on inflammation and intestinal fibrosis (IF), but also on the production of anti-S. cerevisiae antibodies (ASCA), recognizing oligomannosidic sequences of low degree of polymerization having a terminal α, 1-3 mannose residue.Methods. Murine (C57BL/6, axenic and CEABAC10 expressing human CEACAM6) and cellular (CCD-18Co fibroblast and Caco-2 intestinal epithelial cell) models of induced inflammation and IF (by DSS or TGF-β) were used to evaluate cellular, tissue and systemic responses to yeasts and bacterial strain LF82, invasive adherent strain of E. coli (AIEC) used as control, by histological analysis, RT-q-PCR and determination of ASCA. Alongside, a metagenomic (MTG) analysis of the fecal mycobiota and the determination of ASCA and fecal calprotectin were carried out as part of a case-control study, “MAGIC”. This study included subjects with recently diagnosed CD and in clinical remission in comparison to their healthy first-degree relatives, as well as to matched healthy controls. This study was carried out in collaboration with other research teams, analyzing in particular the bacterial fecal microbiota and carrying out the characterization of AIEC strains.Results. In the mouse model of chemo-induced IF, LF82 worsened inflammation and IF, clinically, microscopically and at the level of gene expression (GE). C. albicans increased the GE especially of markers of inflammation. S. cerevisiae had no effect. In vitro, only epithelial cells responded to TGF-β and/or LF82 and the GE of pro-fibrotic markers was increased, while yeast had no effect on IF. Furthermore, yeasts did not induce the synthesis of ASCA in the different mouse models studied. In the MAGIC clinical study, 41.7% of CD patients carried ASCA, 2.9% of healthy relatives and 1.8% of healthy controls and no difference was observed according to age. Bacterial MTG analysis showed a specific profile in healthy relatives (higher richness and AIEC) vs. controls and MC patients, particularly linked to the presence of symbionts bacteria, but also the higher presence of AIEC vs. controls; patients with CD had lower diversity vs. healthy controls and relatives, as well as the presence of higher AIEC vs. controls. However, the fecal mycobiota was similar between the different groups, whether in relative abundance (notably for C. albicans and S. cerevisiae), or in alpha- beta-diversity. No association between micromycetes and the different parameters evaluated (calprotectin, ASCA, AIEC) was found.Conclusion. These results suggest, within the limits of the models used, that the studied yeasts do not have an impact on IF, unlike LF82, and do not seem responsible for the synthesis of ASCA. The autoantibody hypothesis remains to be further explored. Fecal fungal MTG analysis of the individuals included in the MAGIC study suggests that the changes observed in other studies are a consequence of CD. Indeed, the absence of a specific fungal profile could be explained by the fact that the included subjects suffering from CD had a recent diagnosis and therefore had a little modified fungal profile at this stage of the disease. However, the quality of these data warrants that these results be confirmed in a large cohort of patients with CD followed sequentially at the beginning and throughout the course of the disease

Intérêt du dosage des ß-(1,3)-D-glucanes dans le diagnostic des infections fongiques invasives à levures en néonatalogie

Introduction: Les levuroses invasives (LI) chez le nouveau-né (NN) sont des infections graves et difficiles à diagnostiquer. Les signes cliniques ne sont pas spécifiques et le rendement des hémocultures est faible. Le dosage des b-(1,3)-D-glucanes (BDG) sériques constitue un marqueur fiable pour le diagnostic des infections fongiques invasives de l adulte. Notre objectif était d'évaluer les performances diagnostiques de ce test dans les LI néonatales et son apport dans le suivi thérapeutique. Matériel et méthodes: Une étude rétrospective a été réalisée dans le service de néonatalogie du Centre Hospitalier Universitaire d'Amiens de février 2012 à février 2014. Résultats: Quarante-sept NN (33M, 14F) d'âge gestationnel médian de 30 (27; 31) semaines et de poids de naissance médian 1200 (968; 1700) g ont été inclus et répartis en 3 groupes: 21 NN témoins (CTRL), 20 NN avec levurose probable (PB) et 6 NN avec levurose prouvée (PV) (4 candidoses et 2 malassezioses). Le taux de BDG était plus élevé dans les groupe levuroses (PB+PV) :149 (85; 364) vs. le groupe CTRL 39 (20; 94) pg/ml; p < 0,001. Le seuil optimal suggéré par la courbe ROC était de 106 pg/ml (sensibilité, 61,5%; spécificité, 81%). Le taux de BDG diminuait avec le traitement antifongique et n'était pas corrélé à l'importance de la colonisation dans le groupe PB. La détection des BDG dans le liquide céphalo-rachidien est possible mais son intérêt reste à préciser. Conclusion: Nos résultats sont en faveur de l'utilité de la glucanémie dans le diagnostic et le suivi thérapeutique des levuroses invasives du NN. Cet outil devrait permettre d identifier précocement les patients justifiant d un traitement antifongique.AMIENS-BU Santé (800212102) / SudocSudocFranceF

The Changing Landscape of Invasive Fungal Infections in ICUs: A Need for Risk Stratification to Better Target Antifungal Drugs and the Threat of Resistance

The landscape of invasive candidiasis and invasive aspergillosis has changed dramatically in intensive care units over the past two decades. Today, we are faced with new risk factors such as the emergence of resistance, but are also equipped with new therapeutic strategies and diagnostic tools which are changing epidemiological data and diagnostic algorithms. Some common points need to be addressed: (i) the best way to use microbiological tools and to integrate their results in decisional algorithms; (ii) the need to find the optimum balance between under-diagnosis and overtreatment; (iii) and the need to decipher pathophysiology. In this short review, we will try to illustrate these points

Evaluation of the (1,3)-beta-D-glucan assay for the diagnosis of neonatal invasive yeast infections

International audienceMost newborns in the neonatal intensive care unit (NICU) are premature and at risk of invasive fungal infections (IFIs). Invasive yeast infections (IYIs) are the most common fungal infections in this population. These infections are difficult to diagnose because symptoms are nonspecific, and the sensitivity of blood cultures is low. The serum (1,3)-beta-D-glucan (BDG) assay provides a reliable marker for the diagnosis of IFIs in adults with haematological malignancies. We assessed the diagnostic performance of this test in neonatal IYIs and its contribution to the monitoring of antifungal treatment. A retrospective study was performed in the NICU of the French University Hospital of Amiens from February 2012 to February 2014. Forty-seven neonates (33 males, 14 females) with a median gestational age of 30 weeks (IQR: 27-31) and median birth weight of 1200 g (IQR: 968-1700) were included and divided into three groups: 21 control neonates (CTRL), 20 neonates with probable IYI (PB), and six with proven IYI (PV). Median BDG levels were significantly higher in the global IYI group (PB + PV): 149 pg/ml (IQR: 85-364) vs. CTRL group: 39 pg/ml (IQR: 20-94) (P < .001). The optimal cut-off was 106 pg/ml (sensitivity 61.5%; specificity 81%). BDG levels decreased with antifungal treatment. BDG was detectable in cerebrospinal fluid, but the interest of this for diagnostic purposes remains unclear. Our results suggest that the BDG assay may be useful for the early identification of IYIs in neonates and for monitoring antifungal therapy efficacy

Adherent invasive escherichia coli (aiec) strain lf82, but not candida albicans, plays a profibrogenic role in the intestine

International audienceBACKGROUND: Intestinal fibrosis is a frequent complication of Crohn's disease. However, the factors that cause chronicity and promote fibrogenesis are not yet understood.OBJECTIVE: In the present study, we evaluated the profibrotic effects of adherent-invasive Escherichia coli (AIEC) LF82 strain and Candida albicans in the gut.METHODS: Colonic fibrosis was induced in C57BL/6 mice by administration of three cycles of 2.5% (w/v) dextran sulfate sodium (DSS) for 5 weeks. LF82 and C. albicans were administered orally once at the start of each week or each cycle, respectively. Expression of markers of myofibroblast activation was determined in TGF-β1-stimulated human intestinal epithelial cells (IECs).RESULTS: LF82 administration exacerbated fibrosis in DSS-treated mice, revealed by increased colonic collagen deposition and expression of the profibrotic genes Col1a1, Col3a1, Fn1 and Vim. This was accompanied by enhanced gene expression of proinflammatory cytokines and chemokines, as well as more recruited inflammatory cells into the intestine. LF82 also potentiated TGF-β1-stimulated epithelial-mesenchymal transition and myofibroblast activation in IECs, by further inducing gene expression of the main mesenchymal cell markers FN1 and VIM and downregulating the IEC marker OCLN. Proinflammatory cytokines were overexpressed with LF82 in TGF-β1-stimulated IECs. Conversely, C. albicans did not affect intestinal fibrosis progression in DSS-treated mice or myofibroblast activation in TGF-β1-stimulated IECs.CONCLUSIONS: These results demonstrate that AIEC strain LF82, but not C. albicans, may play a major profibrogenic role in the gut

Chronic Mucocutaneous Candidiasis in Autoimmune Polyendocrine Syndrome Type 1

International audienceAutoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is an autosomal recessive disease caused by mutations in the autoimmune regulator (AIRE) gene, characterized by the clinical triad of chronic mucocutaneous candidiasis (CMC), hypoparathyroidism, and adrenal insufficiency. CMC can be complicated by systemic candidiasis or oral squamous cell carcinoma (SCC), and may lead to death. The role of chronic Candida infection in the etiopathogenesis of oral SCC is unclear. Long-term use of fluconazole has led to the emergence of Candida albicans strains with decreased susceptibility to azoles. CMC is associated with an impaired Th17 cell response; however, it remains unclear whether decreased serum IL-17 and IL-22 levels are related to a defect in cytokine production or to neutralizing autoantibodies resulting from mutations in the AIRE gene

Prospective Observational Study on the Association Between Serum Mannose-Binding Lectin Levels and Severe Outcome in Critically Ill Patients with Pandemic Influenza Type A (H1N1) Infection

International audienceMannose-binding lectin (MBL) plays an important role in the innate immune response. In addition to activating the complement, MBL can induce cytokine production and contribute to a deleterious inflammatory response with severe A(H1N1)pdm09 virus infection. Our aim was to determine if serum MBL levels correlate with the risk of mortality in intensive care units (ICU) patients with A(H1N1)pdm09 infection. Prospective observational study was performed in ICU patients with acute respiratory distress syndrome due to influenza A(H1N1)pdm09 virus. Demographic characteristics and severity indices were recorded at ICU admission. MBL was assayed from blood drawn at influenza diagnosis within 24-48 h following the ICU admission. Outcomes were compared according to MBL levels. Results are expressed as median and interquartile range. Serum MBL levels were studied in 27 patients (age: 56 [IQR 29] years) with severe A(H1N1)pdm09 infection and in 70 healthy controls. Median admission SAPSII and SOFA scores were 49 [IQR 26] and 12 [IQR 5], respectively. Mortality rate after a 30-day was 37%. MBL was significantly higher in non-survivors (3741 [IQR 2336] ng/ml) vs survivors (215 [IQR 1307] ng/ml), p = 0.006, as well as control group (1814 [IQR 2250] ng/ml), p = 0.01. In contrast, MBL levels in survivors group were significantly lower than the controls group (215 [IQR 1307] ng/ml vs. 1814 [IQR 2250] ng/ml, p = 0.005). MBL cut-off > 1870 ng/ml had a sensitivity of 80% and a specificity of 88.2% for mortality [AUC = 0.82 (95% CI 0.63-0.94)]. Kaplan-Meier analysis demonstrated a strong association between MBL levels and mortality (log-rank 7.8, p = 0.005). MBL > 1870 ng/ml was independently associated with mortality (HR = 8.7, 95% CI 1.2-29.1, p = 0.007). This study shows that baseline MBL > 1870 ng/ml is associated with higher mortality in ICU patients with severe A(H1N1)pdm09 infection

Successful outcome of disseminated mucormycosis in a 3-year-old child suffering from acute leukaemia: the role of isavuconazole? A case report.

International audienceBACKGROUND: The use of isavuconazole is approved for the management of invasive aspergillosis and mucormycosis, only in adults, as no paediatric pharmacology studies have been reported to date. Very few paediatric cases have been published concerning the use of isavuconazole. Amphotericin B is the only antifungal agent recommended in paediatric mucormycosis, but adverse effects and especially nephrotoxicity, even with the liposomal formulation, could be problematic. In this context, the use of other antifungal molecules active on Mucorales becomes needful.METHODS: We describe a case of mucormycosis with rapid onset dissemination in a 3-year-old girl recently diagnosed with acute lymphocytic leukaemia. She was successfully treated with isavuconazole alone and then in combination with liposomal amphotericin B. Isavuconazole therapy was guided by therapeutic drug monitoring.CONCLUSIONS: This case offers new perspectives on the potential use of isavuconazole in children with mucormycosis, as an alternative or adjunct to liposomal amphotericin B