Parietal composition of Lichtheimia corymbifera: Differences between spore and germ tube stages and host-pathogen interactions.

The molecular composition and structural organization of the cell wall of filamentous fungi underlie the ability of the host to identify them as pathogens. Although the organization of the fungal cell wall, composed of 90% polysaccharides, is similar from one fungus to another, small variations condition their ability to trigger pattern recognition receptors. Because the incidence of mucormycosis, an emerging life-threatening infection caused by the species of the order Mucorales is increasing worldwide, the precise composition of the cell wall of two strains of Lichtheimia corymbifera was investigated in the early growth stages of germination (spores and germ-tubes) using trimethylsilylation and confocal microscopy. This study also characterizes the response of THP-1 cells to Mucorales. The study identified the presence of uncommon monosaccharides (fucose, galactose, and glucuronic acid) whose respective proportions vary according to the germination stage, revealing early parietal reorganization. Immunofluorescence studies confirmed the exposure of ß-glucan on the surface of swollen spores and germ-tubes. Both spores and germ-tubes of L. corymbifera promoted an early and strong pro-inflammatory response, through TLR-2. Our results show the singularity of the cell wall of the order Mucorales, opening perspectives for the development of specific diagnostic biomarkers.

Lichtheimia corymbifera is a causative agent of mucormycosis, an emerging invasive fungal infection. Deciphering cell wall composition can lead to the identification of a polysaccharide epitope, which could be used as a biomarker, useful for the diagnosis of mucormycosis.

Oleic Acid and Palmitic Acid from Bacteroides thetaiotaomicron and Lactobacillus johnsonii Exhibit Anti-Inflammatory and Antifungal Properties.

A decrease in populations of Bacteroides thetaiotaomicron and Lactobacillus johnsonii is observed during the development of colitis and fungal overgrowth, while restoration of these populations reduces inflammatory parameters and fungal overgrowth in mice. This study investigated the effect of two fatty acids from B. thetaiotaomicron and L. johnsonii on macrophages and Caco-2 cells, as well as their impact on the inflammatory immune response and on Candida glabrata overgrowth in a murine model of dextran sulfate sodium (DSS)-induced colitis. Oleic acid (OA) and palmitic acid (PA) from L. johnsonii and B. thetaiotaomicron were detected during their interaction with epithelial cells from colon samples. OA alone or OA combined with PA (FAs) reduced the expression of proinflammatory mediators in intestinal epithelial Caco-2 cells challenged with DSS. OA alone or FAs increased FFAR1, FFAR2, AMPK, and IL-10 expression in macrophages. Additionally, OA alone or FAs decreased COX-2, TNFα, IL-6, and IL-12 expression in LPS-stimulated macrophages. In the DSS murine model, oral administration of FAs reduced inflammatory parameters, decreased Escherichia coli and Enterococcus faecalis populations, and eliminated C. glabrata from the gut. Overall, these findings provide evidence that OA combined with PA exhibits anti-inflammatory and antifungal properties.

Two New Compounds Containing Pyridinone or Triazine Heterocycles Have Antifungal Properties against Candida albicans.

Candidiasis, caused by the opportunistic yeast Candida albicans, is the most common fungal infection today. Resistance of C. albicans to current antifungal drugs has emerged over the past decade leading to the need for novel antifungal agents. Our aim was to select new antifungal compounds by library-screening methods and to assess their antifungal effects against C. albicans. After screening 90 potential antifungal compounds from JUNIA, a chemical library, two compounds, 1-(4-chlorophenyl)-4-((4-chlorophenyl)amino)-3,6-dimethylpyridin-2(1H)-one (PYR) and (Z)-N-(2-(4,6-dimethoxy-1,3,5-triazin-2-yl)vinyl)-4-methoxyaniline (TRI), were identified as having potential antifungal activity. Treatment with PYR and TRI resulted in a significant reduction of C. albicans bioluminescence as well as the number of fungal colonies, indicating rapid fungicidal activity. These two compounds were also effective against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. PYR and TRI had an inhibitory effect on Candida biofilm formation and reduced the thickness of the mannan cell wall. In a Caenorhabditis elegans infection model, PYR and TRI decreased the mortality of nematodes infected with C. albicans and enhanced the expression of antimicrobial genes that promote C. albicans elimination. Overall, PYR and TRI showed antifungal properties against C. albicans by exerting fungicidal activities and enhancing the antimicrobial gene expression of Caenorhabditis elegans.

Adherent invasive Escherichia coli (AIEC) strain LF82, but not Candida albicans, plays a profibrogenic role in the intestine.

BACKGROUND: Intestinal fibrosis is a frequent complication of Crohn's disease. However, the factors that cause chronicity and promote fibrogenesis are not yet understood. AIMS: 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-ß1-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-ß1-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-ß1-stimulated IECs. Conversely, C. albicans did not affect intestinal fibrosis progression in DSS-treated mice or myofibroblast activation in TGF-ß1-stimulated IECs. CONCLUSIONS: These results demonstrate that AIEC strain LF82, but not C. albicans, may play a major profibrogenic role in the gut.

H89 Treatment Reduces Intestinal Inflammation and Candida albicans Overgrowth in Mice.

Deregulation of the dynamic crosstalk between the gut microbiota, intestinal epithelial cells, and immune cells is critically involved in the development of inflammatory bowel disease and the overgrowth of opportunistic pathogens, including the human opportunistic fungus Candida albicans. In the present study, we assessed the effect of N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), a protein kinase A inhibitor, on the migration of macrophages to C. albicans through dextran sulphate sodium (DSS)-challenged Caco-2 cells. We also investigated the impact of H89 on intestinal inflammation and C. albicans clearance from the gut, and determined the diversity of the gut microbiota in a murine model of DSS-induced colitis. H89 reduced the migration of macrophages to C. albicans through DSS-challenged Caco-2 cells. In addition, H89 decreased C. albicans viability and diminished the expression of pro-inflammatory cytokines and innate immune receptors in macrophages and colonic epithelial Caco-2 cells. In mice with DSS-induced colitis, H89 attenuated the clinical and histological scores of inflammation and promoted the elimination of C. albicans from the gut. H89 administration to mice decreased the overgrowth of Escherichia coli and Enterococcus faecalis populations while Lactobacillus johnsonii populations increased significantly. Overall, H89 reduced intestinal inflammation and promoted the elimination of C. albicans from the gut.

Bacteroides thetaiotaomicron and Lactobacillus johnsonii modulate intestinal inflammation and eliminate fungi via enzymatic hydrolysis of the fungal cell wall.

Alterations to the gut microbiota can cause an amplification of the inflammatory response to intestinal pathogens. We assessed the effect of Bacteroides thetaiotaomicron and Lactobacillus johnsonii on the elimination of Candida species and whether restoration of these two anaerobic bacteria could attenuate the development of colitis in mice. In this study, L. johnsonii and B. thetaiotaomicron interacted directly with Candida species and induced a degradation of the fungal cell wall, mediated via chitinase-like and mannosidase-like activities, which promoted the inhibition of Candida species growth. In the DSS-induced colitis model, oral administration of L. johnsonii and B. thetaiotaomicron to mice reduced the overgrowth of Escherichia coli, Enterococcus faecalis and Candida glabrata populations and resulted in a significant reduction in inflammatory parameters. L. johnsonii and B. thetaiotaomicron decreased pro-inflammatory mediators and enhanced the anti-inflammatory cytokine response with high TLR9 expression and chitinase-like protein-1 activation, which promoted the elimination of C. glabrata from the gut. Overall, these findings provide evidence that L. johnsonii and B. thetaiotaomicron decrease the development of colitis mediated by TLR9 and promote the elimination of C. glabrata from the gut via chitinase-like and mannosidase-like activities.

New Efficient Eco-Friendly Supported Catalysts for the Synthesis of Amides with Antioxidant and Anti-Inflammatory Properties.

A new environmentally friendly approach for the synthesis of idrocilamide (1), a marketed myorelaxant and anti-inflammatory agent, is reported herein. The synthetic strategy involves a solvent-free aminolysis reaction catalyzed by zinc-containing species (ZnCl2 , montmorillonite K10 (MK10) impregnated with ZnCl2 or eco-catalysts). The latter have been prepared from the aerial parts of Lolium perenne L. plants grown on contaminated soils from northern France without and with thermal activation at 120 °C and supported on MK10 (Ecocat1 and Ecocat2, respectively). The best aminolysis catalysts in the current study (ZnCl2 and Ecocat2) were selected for additional aminolyses. Compared to ZnCl2 , Ecocat2 had the advantage of being reusable over five test runs and constituted a sustainable catalyst allowing a green route to idrocilamide. Synthesized derivatives 1-4, 6 and 9 were first evaluated for their effect on reactive oxygen species (ROS) generation from macrophages and displayed antioxidant properties by preventing ROS production. Next, the analysis of the effect of molecules 1-4, 6 and 9 on macrophage migration between epithelial cells to human opportunistic fungus Candida albicans indicated that molecules 2-4, 6 and 9 exert anti-inflammatory properties via reducing macrophage migration while the parent idrocilamide (1) did not show any significant effect. This work opens the way for the discovery of new analogues of idrocilamide with improved properties.

Pyroglutamide-Based P2X7 Receptor Antagonists Targeting Inflammatory Bowel Disease.

This report deals with the design, the synthesis, and the pharmacological evaluation of pyroglutamide-based P2X7 antagonists. A dozen were shown to possess improved properties, among which inhibition of YO-PRO-1/TO-PRO-3 uptake and IL1ß release upon BzATP activation of the receptor and dampening signs of DSS-induced colitis on mice, in comparison with reference antagonist GSK1370319A. Docking study and biological evaluation of synthesized compounds has highlighted new SAR, and low toxicity profiles of pyroglutamides herein described are clues for the finding of a usable h-P2X7 antagonist drug. Such a drug would raise the hope for a cure to many P2X7-dependent pathologies, including inflammatory, neurological, and immune diseases.

Fungal Chitin Reduces Platelet Activation Mediated via TLR8 Stimulation.

Platelets play an important role in the innate immune response. During candidaemia, circulating fungal polysaccharides, including chitin, are released into the bloodstream and can interact with platelets and induce modulation of platelet activities. However, the role of circulating chitin in platelet modulation has not been investigated. The aims of the present study were to assess the effect of fungal chitin on activation, adhesion, aggregation and receptor expression of platelets and their impact on the host defense against Candida albicans. Platelets pre-treated with different concentrations of chitin (10-400 µg/mL) extracted from C. albicans were analyzed in terms of activation, Toll-like receptor (TLR) expression, aggregation and adhesion to C. albicans. Chitin treatment reduced platelet adhesion to C. albicans and neutrophils. P-selectin expression was significantly decreased in platelets challenged with chitin. Aggregation and intracellular Ca2+ influx were also decreased in platelets. TLR8 mRNA and proteins were expressed in platelets pre-treated with chitin when compared to untreated platelets. Overall, chitin purified from C. albicans reduced the adhesion, activation and aggregation of platelets mediated via TLR8 stimulation by decreasing intracellular Ca2+ influx and P-selectin expression.

Intravenous Immunoglobulin Therapy Eliminates Candida albicans and Maintains Intestinal Homeostasis in a Murine Model of Dextran Sulfate Sodium-Induced Colitis.

Intravenous immunoglobulin (IVIg) therapy has diverse anti-inflammatory and immunomodulatory effects and has been employed successfully in autoimmune and inflammatory diseases. The role of IVIg therapy in the modulation of intestinal inflammation and fungal elimination has not been yet investigated. We studied IVIg therapy in a murine model of dextran sulfate sodium (DSS)-induced colitis. Mice received a single oral inoculum of Candida albicans and were exposed to DSS treatment for 2 weeks to induce colitis. All mice received daily IVIg therapy starting on day 1 for 7 days. IVIg therapy not only prevented a loss of body weight caused by the development of colitis but also reduced the severity of intestinal inflammation, as determined by clinical and histological scores. IVIg treatment significantly reduced the Escherichia coli, Enterococcus faecalis, and C. albicans populations in mice. The beneficial effects of IVIg were associated with the suppression of inflammatory cytokine interleukin (IL)-6 and enhancement of IL-10 in the gut. IVIg therapy also led to an increased expression of peroxisome proliferator-activated receptor gamma (PPARγ), while toll-like receptor 4 (TLR-4) expression was reduced. IVIg treatment reduces intestinal inflammation in mice and eliminates C. albicans overgrowth from the gut in association with down-regulation of pro-inflammatory mediators combined with up-regulation of anti-inflammatory cytokines.

A Small Aromatic Compound Has Antifungal Properties and Potential Anti-Inflammatory Effects against Intestinal Inflammation.

Resistance of the opportunistic pathogen Candida albicans to antifungal drugs has increased significantly in recent years. After screening 55 potential antifungal compounds from a chemical library, 2,3-dihydroxy-4-methoxybenzaldehyde (DHMB) was identified as having potential antifungal activity. The properties of DHMB were then assessed in vitro and in vivo against C. albicans overgrowth and intestinal inflammation. Substitution on the aromatic ring of DHMB led to a strong decrease in its biological activity against C. albicans. The MIC of DHMB was highly effective at eliminating C. albicans when compared to that of caspofungin or fluconazole. Additionally, DHMB was also effective against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. DHMB was administered to animals at high doses. This compound was not cytotoxic and was well-tolerated. In experimental dextran sodium sulphate (DSS)-induced colitis in mice, DHMB reduced the clinical and histological score of inflammation and promoted the elimination of C. albicans from the gut. This finding was supported by a decrease in aerobic bacteria while anaerobic bacteria populations were re-established in mice treated with DHMB. DHMB is a small organic molecule with antifungal properties and anti-inflammatory activity by exerting protective effects on intestinal epithelial cells.

A decrease in anaerobic bacteria promotes Candida glabrata overgrowth while ß-glucan treatment restores the gut microbiota and attenuates colitis.

BACKGROUND: The intestinal microbiota plays a crucial role in the maintenance of gut homeostasis. Changes in crosstalk between the intestinal epithelial cells, immune cells and the microbiota are critically involved in the development of inflammatory bowel disease. In the experimental mouse model, the development of colitis induced by dextran sulfate sodium (DSS) promotes overgrowth of the opportunistic yeast pathogen Candida glabrata. Conversely, fungal colonization aggravates inflammatory parameters. In the present study, we explored the effect of C. glabrata colonization on the diversity of the gut microbiota in a DSS-induced colitis model, and determined the impact of soluble ß-glucans on C. glabrata-host interactions. RESULTS: Mice were administered a single inoculum of C. glabrata and were exposed to DSS treatment for 2 weeks in order to induce acute colitis. For ß-glucan treatment, mice were administered with soluble ß-glucans purified from C. glabrata (3 mg per mouse), orally and daily, for 5 days, starting on day 1. The number of C. glabrata colonies and changes in microbiota diversity were assessed in freshly collected stool samples from each tagged mouse, using traditional culture methods based on agar plates. An increase in Escherichia coli and Enterococcus faecalis populations and a reduction in Lactobacillus johnsonii and Bacteroides thetaiotaomicron were observed during colitis development. This decrease in L. johnsonii was significantly accentuated by C. glabrata overgrowth. Oral administration of ß-glucans to mice decreased the overgrowth of aerobic bacteria and IL-1ß expression while L. johnsonii and B. thetaiotaomicron populations increased significantly. ß-glucan treatment increased IL-10 production via PPARγ sensing, promoting the attenuation of colitis and C. glabrata elimination. CONCLUSIONS: This study shows that the colonic inflammation alters the microbial balance, while ß-glucan treatment increases the anaerobic bacteria and promotes colitis attenuation and C. glabrata elimination.

Remodeling of the Candida glabrata cell wall in the gastrointestinal tract affects the gut microbiota and the immune response.

The gastrointestinal (GI) microbiota acts a natural barrier to the proliferation of opportunistic pathogens. Candida glabrata is an opportunistic yeast pathogen that has adapted to colonize all segments of the human GI tract. We observed an increase in Escherichia coli, Enterococcus faecalis, and Bacteroides vulgatus populations, and a decrease in Lactobacillus johnsonii, Bacteroides thetaiotaomicron, and Bifidobacterium animalis in mice with DSS-induced colitis. This reduction was more pronounced for L. johnsonii during C. glabrata overgrowth. In addition, C. glabrata overgrowth increased mouse mortality and inflammatory parameters, and modulated the expression of intestinal receptors and signaling pathways. The C. glabrata cell wall underwent various changes during the course of C. glabrata colonization, and showed a significant increase in chitin. C. glabrata deficient in chitin synthase-3 induced fewer inflammatory parameters than the parental strain during intestinal inflammation. Oral administration of chitin attenuated the impact of colitis, and reduced the number of aerobic bacteria and C. glabrata overgrowth, while chitinase-3-like protein-1 increased. This study provides evidence that inflammation of the gut alters the microbial balance and leads to C. glabrata cell wall remodeling through an increase in chitin, which is involved in promoting persistence of C. glabrata in the gut.

Short fungal fractions of ß-1,3 glucans affect platelet activation.

Platelets are capable of binding, aggregating, and internalizing microorganisms, which enhances the elimination of pathogens from the blood. The yeast Candida albicans is a pathobiont causing life-threatening invasive infections. Its cell wall contains ß-1,3 glucans that are known to trigger a wide range of host cell activities and to circulate during infection. We studied the effect of ß-1,3 glucan fractions (BGFs) consisting of diglucosides (Glc2), tetraglucosides (Glc4), and pentaglucosides (Glc5) on human platelets, their mechanisms of action, and their possible impact on host defenses. The effect of BGFs on the coagulation process was determined by measuring thrombin generation. Platelets pretreated with BGFs were analyzed in terms of activation, receptor expression, aggregation, and adhesion to neutrophils and to C. albicans The results show that BGFs affected the endogenous thrombin potential in a concentration-dependent manner. For platelet activation, BGFs at a low concentration (2 µmol/l) reduced ATP release and prevented the phosphorylation of protein kinase C. BGFs diminished the expression of P-selectin and the activation of αIIbß3 BGFs decreased platelet aggregation and the interaction between thrombin-stimulated platelets and neutrophils, fibrinogen, and C. albicans GLc5 decreased ATP release and TGF-ß1 production in response to TLR4 upregulation in thrombin-stimulated platelets, but TLR4 blockage abolished the effect of BGFs on platelets. This study provides evidence that fungal pentaglucosides modulate platelet activity mediated via TLR4 stimulation and reduce platelet-neutrophil interaction.