Composition Of Fungal Microbiota Research Articles

Effects and microbiota changes following oral lyophilized fecal microbiota transplantation in children with autism spectrum disorder.

Autism spectrum disorder (ASD) is a group of heterogeneous neurodevelopmental disorders that is characterized by core features in social communication impairment and restricted, repetitive sensory-motor behaviors. This study aimed to further investigate the utilization of fecal microbiota transplantation (FMT) in children with ASD, both with and without gastrointestinal (GI) symptoms, evaluate the effect of FMT and analyze the alterations in bacterial and fungal composition within the gut microbiota. A total of 38 children diagnosed with ASD participated in the study and underwent oral lyophilized FMT treatment. The dosage of the FMT treatment was determined based on a ratio of 1 g of donor stool per 1 kg of recipient body weight, with a frequency of once every 4 weeks for a total of 12 weeks. In addition, 30 healthy controls (HC) were included in the analysis. The clinical efficacy of FMT was evaluated, while the composition of fecal bacteria and fungi was determined using 16S rRNA and ITS gene sequencing methods. Median age of the 38 children with ASD was 7 years. Among these children, 84.2% (32 of 38) were boys and 81.6% (31 of 38) exhibited GI symptoms, with indigestion, constipation and diarrhea being the most common symptoms. Sample collections and assessments were conducted at baseline (week 0), post-treatment (week 12) and follow-up (week 20). At the end of the follow-up phase after FMT treatment, the autism behavior checklist (ABC) scores decreased by 23% from baseline, and there was a 10% reduction in scores on the childhood autism rating scale (CARS), a 6% reduction in scores on the social responsiveness scale (SRS) and a 10% reduction in scores on the sleep disturbance scale for children (SDSC). In addition, short-term adverse events observed included vomiting and fever in 2 participants, which were self-limiting and resolved within 24 h, and no long-term adverse events were observed. Although there was no significant difference in alpha and beta diversity in children with ASD before and after FMT therapy, the FMT treatment resulted in alterations in the relative abundances of various bacterial and fungal genera in the samples of ASD patients. Comparisons between children with ASD and healthy controls (HC) revealed statistically significant differences in microbial abundance before and after FMT. Blautia, Sellimonas, Saccharomycopsis and Cystobasidium were more abundant in children with ASD than in HC, while Dorea were less abundant. After FMT treatment, levels of Blautia, Sellimonas, Saccharomycopsis and Cystobasidium decreased, while levels of Dorea increased. Moreover, the increased abundances of Fusicatenibacter, Erysipelotrichaceae_UCG-003, Saccharomyces, Rhodotorula, Cutaneotrichosporon and Zygosaccharomyces were negatively correlated with the scores of ASD core symptoms. Oral lyophilized FMT could improve GI and ASD related symptoms, as well as sleep disturbances, and alter the gut bacterial and fungal microbiota composition in children with ASD. Chinese Clinical Trial Registry, ChiCTR2200055943. Registered 28 January 2022, www.chictr.org.cn.

Characterization of intestinal fungal community diversity in people living with HIV/AIDS (PLWHA)

Acquired Immune Deficiency Syndrome (AIDS) is a highly dangerous infectious disease caused by the Human Immunodeficiency Virus (HIV), a virus that attacks the human immune system. To explore the correlation between intestinal fungal community and immune function (Immune cells and inflammatory factors) in people living with HIV/AIDS (PLWHA). The feces and blood samples were collected from two groups of subjects: PLWHA and healthy controls. High-throughput sequencing of the internal transcribed spacer 1, flow cytometry, and ELISA were performed to analyze the differences and correlations between fungal microbiota, cellular immune status and serum inflammatory factors in the two groups. There were significant differences in the composition of fungal microbiota between the two groups. The relative abundance of Candida, Bjerkandera, and Xeromyces in PLWHA was significantly higher than that of healthy volunteers (P < 0.01), while the relative abundance of Mycospaerella, Xeroxysium, Penicillium, and Glomerella in PLWHA was significantly lower than that of healthy volunteers. The correlation analysis results show that Mycospaerella and Xeromyces are significantly positively correlated with CD4+/CD8+ T cells and the anti-inflammatory cytokine IL-4. On the other hand, Candida was positively correlated with pro-inflammatory factors negatively correlated with CD4+/CD8+ T cells and the anti-inflammatory cytokine IL-4, while it is positively correlated with pro-inflammatory cytokines. The significant increase in the relative abundance of Candida may be one of the important causes of intestinal damage in PLWHA. The results of this study contribute to the understanding of the relationship between fungal microbiota structure and immune function in the gut ecology of PLWHA.

Fungal Microbiota Composition in Inflammatory Bowel Disease Patients: Characterization in Different Phenotypes and Correlation With Clinical Activity and Disease Course.

There is growing evidence of the role of the mycobiome in inflammatory bowel disease (IBD). Variations within phenotypes and activity and with prognosis have been poorly studied. A total of 111 individuals were prospectively enrolled: 89 IBD patients (52 ulcerative colitis and 37 Crohn's disease [CD]) and 22 healthy individuals. Disease characteristics were collected and a fecal calprotectin >100 μg/mg was considered indicative of activity. A subset of patients was followed for 6 ± 2 years. Disease course was designated as either complicated or uncomplicated based on the need of intensified medication and/or surgery. ITS sequencing was performed targeting the ITS1 region. We found lower Ascomycota/Basidiomycota ratio in IBD. Patients showed a marked increase in Candida dublinensis and Ca albicans and were depleted of Aspergillus rubrobrunneus and Penicillium brevicompactum (P ≤ .001) Saccharomyces was predominant in total colitis and Penicillium in proctitis. Several Penicillium species were depleted in total colitis vs proctitis. Ileal CD patients were enriched in Debaromyces hansenii and depleted of Ca tropicalis (P ≤ .001). Ca albicans was overrepresented in inflammatory (B1) vs fibrostenosing (B2) CD. Ca dublinensis was more abundant in active patients and correlated positively with fecal calprotectin and neutrophil gelatinase-associated lipocalin, while S pastorianus correlated inversely with activity. Ca sake was associated with complicated disease and increased abundance of Cryptococcus carnescens with the need for surgery in CD. This study shows important differences in the mycobiome in IBD and within phenotypes. Selected fungal species were associated with complicated disease and the need of surgery in CD. This work adds to our understanding of the role of fungi in IBD, with potential clinical implications.

Microplastic ingestion perturbs the microbiome of Aedes albopictus (Diptera: Culicidae) and Aedes aegypti.

Microplastics (MPs) are common environmental pollutants; however, little is known about their effects after ingestion by insects. Here we fed Aedes (Stegomyia) aegypti (L.) and Aedes (Stegomyia) albopictus (Skuse) mosquito larvae 1 µm polystyrene MPs and examined the impacts of ingestion on adult emergence rates, gut damage, and fungal and bacterial microbiota. Results show that MPs accumulate in the larval guts, resulting in gut damage. However, little impact on adult emergence rates was observed. MPs are also found in adult guts postemergence from the pupal stage, and adults expel MPs in their frass after obtaining sugar meals. Moreover, MPs effects on insect microbiomes need to be better defined. To address this knowledge gap, we investigated the relationship between MP ingestion and the microbial communities in Ae. albopictus and Ae. aegypti. The microbiota composition was altered by the ingestion of increasing concentrations of MPs. Amplicon sequence variants (ASVs) that contributed to differences in the bacterial and fungal microbiota composition between MP treatments were from the genera Elizabethkingia and Aspergillus, respectively. Furthermore, a decrease in the alpha diversity of the fungal and bacterial microbiota was observed in treatments where larvae ingested MPs. These results highlight the potential for the bacterial and fungal constituents in the mosquito microbiome to respond differently to the ingestion of MPs. Based on our findings and the effects of MP ingestion on the mosquito host micro- and mycobiome, MP pollution could impact the vector competence of important mosquito-transmitted viruses and parasites that cause human and animal diseases.

Neglected mycobiome in HIV infection: Alterations, common fungal diseases and antifungal immunity.

Human immunodeficiency virus (HIV) infection might have effects on both the human bacteriome and mycobiome. Although many studies have focused on alteration of the bacteriome in HIV infection, only a handful of studies have also characterized the composition of the mycobiome in HIV-infected individuals. Studies have shown that compromised immunity in HIV infection might contribute to the development of opportunistic fungal infections. Despite effective antiretroviral therapy (ART), opportunistic fungal infections continue to be a major cause of HIV-related mortality. Human immune responses are known to play a critical role in controlling fungal infections. However, the effect of HIV infection on innate and adaptive antifungal immunity remains unclear. Here, we review recent advances in understanding of the fungal microbiota composition and common fungal diseases in the setting of HIV. Moreover, we discuss innate and adaptive antifungal immunity in HIV infection.

527 Characteristics of the gut microbiome in solid organ transplant recipients

Solid organ transplantation is the ultimate life-saving intervention in patients with end stage organ damage. However, despite revolutionary advances in transplant medicine, complications such as allograft rejection, malignancy, and disseminated infection continue be a major challenge. A growing body of evidence suggests a potential influence of microbial dysbiosis on transplant outcomes. We therefore aimed to investigate the gut microbiome of solid organ transplant recipients for comparison with healthy controls to identify possible dysbiosis. Microbial genomic data, both bacterial and fungal, was generated from fecal samples of 20 solid organ transplant recipients and 20 matched healthy controls. Analyses included testing for differences in microbial diversity measures and relatively abundant species between cohorts. The bacterial median Shannon diversity index, a measure for alpha diversity of the gut microbiome, was significantly higher in solid organ transplant samples with a median of 3.125 versus 2.449 for healthy controls (p<0.05). Additionally, principal coordinate analyses, based on Bray-Curtis distance, displayed significant differences in the bacterial and fungal microbiota composition between stool of transplant patients and healthy controls (PCo1 vs. PCo2, p<0.05). Furthermore, several alterations in abundance existed at different taxonomic levels, including a a 15-fold increased abundance of Clostridium perfringens (p<0.0001), a 3-fold increased abundance of Staph epidermidis (p<0.0001), and 2-fold increased abundance of Staph aureus (p<0.001) at the species level in transplant patients. Ultimately, we demonstrated that solid organ transplant recipients have gut microbiome dysbiosis, characterized by an increase in microbial diversity and several alterations in taxa abundance. This is in discordance with current trends in microbiome research that associate lower diversity with worse health outcomes; however, it supports the emerging role of the microbiome as a therapeutic target.

Effect of Probiotic Fungi against Cognitive Impairment in Mice via Regulation of the Fungal Microbiota-Gut-Brain Axis.

The fungal microbiota may be involved in the regulation of cognition and behavior, while the role of probiotic fungi against cognitive impairment is unclear. Here, we explored the idea that probiotic Saccharomyces boulardii could participate in the regulation of microglia-induced neuroinflammation in Alzheimer's disease (AD) model mice. Cognitive deficits, deposits of amyloid-β (Aβ) and phosphorylation of tau, synaptic plasticity, microglia activation, and neuroinflammatory reactions were observed. The expression levels of Toll-like receptors (TLRs) pathway-related proteins were detected. Meanwhile, intestinal barrier integrity and fungal microbiota composition were evaluated. Our results showed fungal microbiota dysbiosis in APP/PS1 mice, which might result in the neuroinflammation of AD. The increased levels of interleukin (IL)-6, IL-1β, and cluster of differentiation 11b (CD11b) were observed in APP/PS1 mice, which were associated with activation of microglia, indicative of a broader recognition of neuroinflammation mediated by fungal microbiota compared to hitherto appreciated. Probiotic S. boulardii treatment improved dysbiosis, alleviated the neuroinflammation as well as synaptic injury, and ultimately improved cognitive impairment. Moreover, S. boulardii therapy could inhibit microglia activation and the TLRs pathway, which were reversed by antifungal treatment. These findings revealed that S. boulardii actively participated in regulating the TLRs pathway to inhibit the neuroinflammation via the gut-brain axis.

Fungal Microbiota Dysbiosis and Ecological Alterations in Gastric Cancer.

Changes in bacteriome composition have a strong association with gastric cancer (GC). However, the relationship between stomach fungal microbiota composition and human host immune factors remains largely unknown. With high-throughput internal transcribed spacer region 2 (ITS2) sequencing, we characterized gastric fungal microbiome among the GC (n = 22), matched para-GC (n = 22), and healthy individuals (n = 11). A total of 4.5 million valid tags were generated and stratified into 1,631 operational taxonomic units (OTUs), and 10 phyla and 301 genera were identified. The presence of GC was associated with a distinct gastric fungal mycobiome signature, characterized by a decreased biodiversity and richness and significant differences in fungal composition. In addition, fungal dysbiosis was reflected by the increased ratio of Basidiomycota to Ascomycota and a higher proportion of opportunistic fungi, such as Cutaneotrichosporon and Malassezia, as well as the loss of Rhizopus and Rhodotorula during the progression of cancers. A panel of GC-associated fungi (e.g., Cutaneotrichosporon and Rhodotorula) was found to adequately exhibit diagnostic value. Furthermore, the mRNA levels of cytokines and chemokines were detected and correlated with the specific fungal dysbiosis, indicating the possible mechanism of GC. This study reveals GC-associated mycobiome dysbiosis characterized by altered fungal composition and ecology and suggests that the fungal mycobiome might play a role in the pathogenesis of GC.

P712 Fungal microbiota composition in Inflammatory Bowel Disease patients in a Norwegian cohort: characterization of disease phenotypes and correlation with clinical activity and disease course

Abstract Background There is growing evidence of the role of the fungal microbiota in the pathogenesis of IBD, but a definite pattern defining the mycobiome in IBD is currently lacking. In addition, the variations within the different phenotypes as well as the correlation between fungal composition and disease outcomes has been poorly characterized. Our aim is to evaluate the fungal composition within the different IBD phenotypes, the changes with disease activity and the association with disease outcomes. Methods This prospective study presents sequencing of the faecal fungi of 111 individuals: 89 IBD (52 UC/37 CD) and 22 HC. Demographics,medication,Montreal Classification and disease history was collected. A fCalpro&amp;gt;100 was considered active disease. A subset of IBD patients was followed clinically (6±2 y) and classified as either “Complicated” or “Uncomplicated” based on the need of intensified medication and/or surgery. Sequencing was done on amplicons targeting the ITS1 region of fungal DNA on a Illumina MiSeq sequencer. Chosen OTUs were compiled taxonomically.Data analysis was performed in R(phyloseq and deSeq2-packages). Results We found significant variations in the fungal microbiota composition in the different IBD phenotypes(Fig1) In UC, Saccharomyces was predominant in pancolitis (E3), while Penicillium was more abundant in proctitis(E1) and Galactomyces in left-side UC (E2)(Pan.A). At species level, Rhodotorula mucilaginosa was significantly depleted in E3 (p≤0.05)(Pan.B) In CD, Aspergillus was predominant in ileal affection(L1) while Candida and Rhodotorula genus were more abundant in L2-L3.Patients with structuring phenotype(B2) were depleted of Apergillus and Rodhotorula (Pan.A). At species level, ileal (L1) patients were depleted of Candida tropicalis and Penicillium kudriavzevii. B1 patients had a marked predominance of Candida albicans vs B2(p≤0.01)(Pan.B) The mycobiome correlation with disease activity is depicted (Pan.C). Candida dublinensis was overrepresented in activity, while Saccharomyces pastorianus was depleted(p≤0.01) The correlation of the mycobiome with disease outcomes is represented in Pan.D. Penicillium glabrum was significantly overrepresented in patients with a complicated course. The abundance of Candida tropicalis and D. nepalensis was correlated with the need for surgery. Conclusion This study shows important differences in the fungal microbiota composition in the different IBD phenotypes. Some species are clearly correlated with the activity of the disease and worse clinical outcomes suggesting a potential deleterious role.Candida tropicalis was associated with the need of surgery in CD. This in-depth characterization of the mycobiome serves as a significant addition to the understanding of the role of fungi in IBD.

Differentiation of endospheric microbiota in ancient and modern wheat cultivar roots.

Modern plant breeding and agrosystems artificialization could have altered plants' ability to filter and recruit beneficial microorganisms in its microbiota. Thus, compared to modern cultivars, we hypothesized that root-endosphere microbiota in modern wheat cultivars are less resistant to colonization by fungi and bacteria and thus more susceptible to also recruit more pathogens. We used an in-field experimental design including six wheat varieties (three ancient vs. three modern) grown in monoculture and in mixture (three replicates each). Endospheric microbiota of wheat roots were analyzed on four individuals sampled randomly in each plot. Composition-based clustering of sequences was then characterized from amplicon mass-sequencing. We show that the bacterial and fungal microbiota composition in wheat roots differed between ancient and modern wheat cultivar categories. However, the responses observed varied with the group considered. Modern cultivars harbored higher richness of bacterial and fungal pathogens than ancient cultivars. Both cultivar types displayed specific indicator species. A synergistic effect was identified in mixtures of modern cultivars with a higher root endospheric mycobiota richness than expected from a null model. The present study shows the effect of plant breeding on the microbiota associated plant roots. The results call for making a diagnosis of the cultivar's endospheric-microbiota composition. These new results also suggest the importance of a holobiont-vision while considering plant selection in crops and call for better integration of symbiosis in the development of next-generation agricultural practices.

Impacts of Sodium Arsenite on Wood Microbiota of Esca-Diseased Grapevines.

Although sodium arsenite was widely used in Europe until its ban in 2003, its effects on microorganisms is not clearly understood. To improve our understanding of sodium arsenite curative effect on GTDs, grapevines displaying esca-foliar symptoms from different French regions (Alsace, Champagne, Languedoc) were treated or not with sodium arsenite, and analyzed for their wood microbiota. Using metabarcoding, we identified the fungal and bacterial taxa composition of microbiota colonizing woody trunk tissues. Large differences in fungal microbiota composition between treated and untreated grapevines were observed while no major impacts were observed on bacteria microbiota. The main fungal species detected in untreated necrotic woody tissues was Fomitiporia mediterranea (63–94%), a fungal pathogen associated with esca. The relative abundance of this fungal species significantly decreased after sodium arsenite treatment in the three vineyards, in particular in white-rot necrotic tissues and their borders (−90%). F. mediterranea was the most sensitive to sodium arsenite among fungi from grapevine woody tissues. These results strongly suggest that the effect of sodium arsenite on GTDs is due to its ability to efficiently and almost specifically eliminate F. mediterranea from white-rot necrotic tissues, allowing saprobic fungi to colonize the tissues previously occupied by this pathogenic fungus.

Investigation of the microbiota associated with ungerminated and germinated Norwegian barley cultivars with focus on lactic acid bacteria

The microbial community of ungerminated and germinated barley grains from three different cultivars grown at four different locations in Norway was investigated by culture dependent and culture independent methods. Lactic acid bacteria (LAB) was focused in this study and was isolated from germinated barley. The number of LAB ranged between 2.8 and 4.6 log cfu/g in ungerminated grains and between 4.9 and 6.3 log cfu/g in germinated grains. In total 66 out of 190 isolates were Gram+, catalase-negative and presumptive LAB. The LAB isolates were by 16S rRNA sequencing identified to be Carnobacterium maltaromaticum (6), Lactococcus lactis (2), Enterococcus sp. (1) and Leuconostoc sp. (57). Germination significantly influenced the bacterial composition. Regarding the different cultivars and growth places no significant difference in bacterial composition was seen. The most abundant bacterial genus was Pantoea (18.5% of the total sequences), followed by Rhizobium (10.1%) and Sphingomonas (9.9%). Fungal composition was significantly influenced by the germination process and the cultivation place, but no significant difference in fungal composition was detected between the 3 cultivars. The most abundant fungal genera were Cryptococcus (43.8% of all the sequences), Cladosporium (8.2%), Pyrenophora (7.4%) and Vagicola (6.3%). This study revealed knowledge of barley grain associated microbes of Norwegian barley that can be useful to control the malt quality. Germination affected both bacterial and fungal microbiota composition. No difference in bacterial microbiota composition was seen regarding cultivars and cultivation place, however, the fungal microbiota composition was significantly influenced by the cultivation place. Differences in fungal community of ungerminated and germinated barley samples of different geographical locations were more pronounced than differences in bacterial communities.

Bacterial and Fungal Profiles as Markers of Infliximab Drug Response in Inflammatory Bowel Disease.

Inflammatory bowel diseases [IBDs], Crohn's disease [CD] and ulcerative colitis [UC], are globally increasing chronic gastro-intestinal inflammatory disorders associated with altered gut microbiota. Infliximab [IFX], a tumour necrosis factor [TNF]-alpha blocker, is used to treat IBD patients successfully, though one-third of the patients do not respond to therapy. No reliable biomarkers are available for prediction of IFX response. Our aims were to investigate the faecal bacterial and fungal communities during IFX therapy and find predictors for IFX treatment response in IBD patients. A total of 72 IBD patients [25 CD and 47 UC] started IFX therapy and were followed for 1 year or until IFX treatment was discontinued. An amplicon sequencing approach, targeting the bacterial 16S rRNA gene and fungal ITS 1 region separately, was used to determine the microbiota profiles in faecal samples collected before IFX therapy and 2, 6, and 12 weeks and 1 year after initiation of therapy. The response to IFX was evaluated by colonoscopy and clinically at 12 weeks after initiation. Both faecal bacterial and fungal profiles differed significantly between response groups before start of IFX treatment. Non-responders had lower abundances of short chain fatty acid producers, particularly of the class Clostridia, and higher abundances of pro-inflammatory bacteria and fungi, such as the genus Candida, compared with responders. This was further indicated by bacterial taxa predicting the response in both CD and UC patients [area under the curve >0.8]. Faecal bacterial and fungal microbiota composition could provide a predictive tool to estimate IFX response in IBD patients.

Plant host and drought shape the root associated fungal microbiota in rice.

Background and AimWater is an increasingly scarce resource while some crops, such as paddy rice, require large amounts of water to maintain grain production. A better understanding of rice drought adaptation and tolerance mechanisms could help to reduce this problem. There is evidence of a possible role of root-associated fungi in drought adaptation. Here, we analyzed the endospheric fungal microbiota composition in rice and its relation to plant genotype and drought.MethodsFifteen rice genotypes (Oryza sativa ssp. indica) were grown in the field, under well-watered conditions or exposed to a drought period during flowering. The effect of genotype and treatment on the root fungal microbiota composition was analyzed by 18S ribosomal DNA high throughput sequencing. Grain yield was determined after plant maturation.ResultsThere was a host genotype effect on the fungal community composition. Drought altered the composition of the root-associated fungal community and increased fungal biodiversity. The majority of OTUs identified belonged to the Pezizomycotina subphylum and 37 of these significantly correlated with a higher plant yield under drought, one of them being assigned to Arthrinium phaeospermum.ConclusionThis study shows that both plant genotype and drought affect the root-associated fungal community in rice and that some fungi correlate with improved drought tolerance. This work opens new opportunities for basic research on the understanding of how the host affects microbiota recruitment as well as the possible use of specific fungi to improve drought tolerance in rice.

GI Tract Mycobiome in Chronic Hepatitis C Virus Infection : A Case Control Study

Background: Human microbiota including intestinal fungi (mycobiota) plays an important role in health and disease. Mycobiome is a term refers to the genetic composition of fungal microbiota. The relation of intestinal mycobiota to chronic viral hepatitis and its progression has not yet been totally explored. Objectives: This study was designed to compare GI fungal composition and fungal genetic load (mycobiome load) in patients with chronic hepatitis C virus (HCV) infection including liver cirrhosis and healthy subjects. Methodology: Stool samples were collected from patients with varying degrees of chronic HCV infection. Sabouraud dextrose agar was used for culture detection of fungi. Real-time PCR was done for estimation of mycobiome load in patients with chronic HCV infection, HCV cirrhosis and in healthy control. Results: This study enrolled 53 patients with chronic HCV infection including 27 patients with chronic HCV hepatitis and 26 patients with HCV liver cirrhosis. Fifty-five subjects were considered as healthy controls. There is a significant increase in mycobiome load in patients with chronic HCV infection including patients with cirrhosis more than the control group (P value <0.05). By culture method, Candida species were obtained with more frequent isolation in HCV patients. There was an increase in the non albicans Candida in chronic HCV cirrhosis group more than albicans Candida. Conclusion: HCV patients are more predisposed to candidal colonization than normal subjects. The load of enteric mycobiome is increased in chronic HCV patients. The load of GI mycobiome may increase with the progress of HCV infection.

Gut fungal microbiota: the Yin and Yang of inflammatory bowel disease.

The prevalence of inflammatory bowel diseases (IBD) has been steadily increasing since 1960. They are widespread throughout Europe, North America, China, and Japan and are emerging as a global disease. The equilibrium among epithelial cells, the immune system, and the related microbiota seems to be paramount in ensuring the absence of these IBD. The role of bacteria in the setting of the gut microbiota has been thoroughly documented, but the role of fungi, which are less abundant, needs to be investigated. Our understanding of the fungal microbiota composition and its impact on IBD has greatly increased in the past 8 years. In this review, we compiled data obtained for the composition of fungal gut microbiota. Special attention was paid to the various effects of this microbial community on the IBD, i.e., the mechanisms and immune pathways involved in these interactions.

Dysbiosis of Gut Fungal Microbiota is Associated With Mucosal Inflammation in Crohn’s Disease

We aim to characterize the fungal microbiota in the intestinal mucosa and feces in patients with Crohn's disease (CD). Fungi represent a diverse microbial community in the human intestine and might play a role in the pathogenesis of CD; however, little is known about the structure and composition of the fungal microbiota especially adhering to the intestinal mucosa in CD patient. Nineteen patients with active CD and 7 healthy individuals were recruited in this study. The mucosa-associated and fecal fungal microbiotas in CD patients were analyzed using culture-independent community fingerprint techniques. The fungal richness and diversity were significantly elevated in the inflamed mucosa compared with the noninflamed mucosa. The predominant fungal composition in the inflamed mucosa was strikingly altered, mainly characterized by expansion in the proportions of Candida spp., Gibberella moniliformis, Alternaria brassicicola, and Cryptococcus neoformans. The fecal fungal community was perturbed in CD patients as accompanied by increased fungal diversity and prevalence in Candida albicans, Aspergillus clavatus, and C. neoformans. The species richness and diversity of the mucosal fungal community were associated with the expression of TNF-α, IFN-γ, or IL-10 (P<0.05). The diversity of the fecal fungal microbiota positively correlated with serum C-reactive protein and CD activity index (P<0.05). This study first demonstrates that the fungal microbiota in the inflamed mucosa is distinguishable from that of the noninflamed area. Shifts of gut fungal microbiota composition may be associated with mucosal inflammation and disease activity of CD. Our data would provide novel insights into understanding the potential of gut fungal microbiota in the pathogenesis of CD.

Fungi and inflammatory bowel diseases: Alterations of composition and diversity

Objective. Altered bacterial diversity of the intestinal mucosa-associated microbiota may reflect the net influence of lifestyle factors associated with the development of chronic inflammatory bowel diseases (IBD). While a reduced bacterial diversity has been reported in IBD, little is known about the fungal microbiota. The aim of this study was to carry out a systematic analysis of intestinal fungal microbiota in IBD. Material and methods. The mucosa-associated fungal microbiota of 104 colonic biopsy tissues from 47 controls and 57 IBD patients was investigated using metagenomic 18S rDNA-based denaturing gradient gel electrophoresis (DGGE), clone libraries, sequencing, and in situ hybridization techniques. Results. Fungi-specific 18S rDNA signatures could be detected in all 104 patients, accounting for only a small proportion of the intestinal microbiota (0.02% of the mucosal and 0.03% of the fecal microbiota). An overall fungal biodiversity of 43 different operational taxonomic units (OTUs) was found in the clone libraries. The qualitative composition of fungal microbiota was different between patients with IBD and controls. The DGGE profiles showed a higher mean fungal diversity in patients with Crohn's disease (CD) in comparison with controls (10.8±3.1 versus 6.2±2.4 for CD, p ≤ 0.001). No disease-specific fungal species were found in the CD and ulcerative colitis (UC) group. Conclusions. Diverse fungal species are part of the normal enteric microbiota, but diversity is increased and composition of the fungal communities varies in IBD. Further work is needed to investigate whether the alteration of the fungal flora in IBD is secondary to an imbalanced bacterial microbiota or an independent etiologic factor.