Relationship between duodenal microbiota composition, clinical features at diagnosis, and persistent symptoms in adult Coeliac disease

Small intestinal microbiota: from taxonomic composition to metabolism

The small intestinal microbiota (SIM) is essential for gastrointestinal health, influencing digestion, immune modulation, and nutrient metabolism. Unlike the colonic microbiota, the SIM has been poorly characterized due to sampling challenges and ethical considerations. Current evidence suggests that the SIM consists of five core genera and additional segment-specific taxa. These bacteria closely interact with the human host, regulating nutrient absorption and metabolism. Recent work suggests the presence of two forms of small intestinal bacterial overgrowth, one dominated by oral bacteria (SIOBO) and a second dominated by coliform bacteria. Less invasive sampling techniques, omics approaches, and mechanistic studies will allow a more comprehensive understanding of the SIM, paving the way for interventions engineering the SIM towards better health.

Celiac disease gut microbiome studies in the third millennium: reviewing the findings and gaps of available literature

Celiac disease is an autoimmune enteropathy caused by the ingestion of minute amounts of gluten in a subset of genetically predisposed individuals. Its onset occurs at different ages and with variable symptoms. The gut microbiome may contribute to this variability. This review aims to provide an overview of the available research on celiac disease gut microbiome and identify the knowledge gap that could guide future studies. Following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis extension for Scoping Reviews (PRISMA-ScR), four electronic databases were searched for literature from January 2000 to July 2023 addressing celiac disease gut microbiome characterization using next-generation sequencing (NGS) approaches. From the 489 publications retrieved, 48 publications were selected and analyzed, focusing on sample characterization (patients, controls, and tissues) and methodologies used for NGS microbiome analysis and characterization. The majority of the selected publications regarded children and adults, and four were randomized clinical trials. The number of participants per study greatly varied and was typically low. Feces were the most frequently tested sample matrix, and duodenal samples were analyzed in one-third of the studies. Incomplete and diverse information on the methodological approaches and gut microbiome results was broadly observed. While similar trends regarding the relative abundance of some phyla, such as Pseudomonadota (former Proteobacteria), were detected in some studies, others contradicted those results. The observed high variability of technical approaches and possibly low power and sample sizes may prevent reaching a consensus on celiac disease gut microbiome composition. Standardization of research protocols to allow reproducibility and comparability is required, as interdisciplinary collaborations to further data analysis, interpretation, and, more importantly, health outcome prediction or improvement.

Evaluation of gut microbiota of iranian patients with celiac disease, non-celiac wheat sensitivity, and irritable bowel syndrome: are there any similarities?

BACKGROUND AND AIMS

Individuals with celiac disease (CD), non-celiac wheat sensitivity (NCWS), and irritable bowel syndrome (IBS), show overlapping clinical symptoms and experience gut dysbiosis. A limited number of studies so far compared the gut microbiota among these intestinal conditions. This study aimed to investigate the similarities in the gut microbiota among patients with CD, NCWS, and IBS in comparison to healthy controls (HC).

MATERIALS AND METHODS

In this prospective study, in total 72 adult subjects, including CD (n = 15), NCWS (n = 12), IBS (n = 30), and HC (n = 15) were recruited. Fecal samples were collected from each individual. A quantitative real-time PCR (qPCR) test using 16S ribosomal RNA was conducted on stool samples to assess the relative abundance of Firmicutes, Bacteroidetes, Bifidobacterium spp., and Lactobacillus spp.

RESULTS

In all groups, Firmicutes and Lactobacillus spp. had the highest and lowest relative abundance respectively. The phylum Firmicutes had a higher relative abundance in CD patients than other groups. On the other hand, the phylum Bacteroidetes had the highest relative abundance among healthy subjects but the lowest in patients with NCWS. The relative abundance of Bifidobacterium spp. was lower in subjects with CD (P = 0.035) and IBS (P = 0.001) compared to the HCs. Also, the alteration of Firmicutes to Bacteroidetes ratio (F/B ratio) was statistically significant in NCWS and CD patients compared to the HCs (P = 0.05).

CONCLUSION

The principal coordinate analysis (PCoA), as a powerful multivariate analysis, suggested that the investigated gut microbial profile of patients with IBS and NCWS share more similarities to the HCs. In contrast, patients with CD had the most dissimilarity compared to the other groups in the context of the studied gut microbiota.

High Prevalence of Functional Gastrointestinal Disorders in Celiac Patients with Persistent Symptoms on a Gluten-Free Diet: A 20-Year Follow-Up Study

BACKGROUND

Ongoing symptoms in treated celiac disease (CD) are frequent and are commonly thought of as being due to infractions to a gluten-free diet (GFD) or complications.

AIMS

To study the etiology and natural history of clinically relevant events (CREs) throughout follow-up and identify predictors thereof to guide follow-up.

METHODS

CREs (symptoms/signs requiring diagnostic/therapeutic interventions) occurring in celiac patients between January-2000 and May-2021 were retrospectively collected between June and September 2021 and analysed.

RESULTS

One-hundred-and-eighty-nine adult patients (133 F, age at diagnosis 36 ± 13 years, median follow-up 103 months, IQR 54-156) were enrolled. CREs were very common (88/189, 47%), but hardly due to poor GFD adherence (4%) or complications (2%). Interestingly, leading etiologies were functional gastrointestinal disorders (30%), reflux disease (18%) and micronutrient deficiencies (10%). Age at diagnosis ≥ 45 years (HR 1.68, 95%CI 1.05-2.69, p = 0.03) and classical pattern of CD (HR 1.63, 95%CI 1.04-2.54, p = 0.03) were predictors of CREs on a multivariable Cox model. At 5 years, 46% of classical patients ≥ 45 years old at diagnosis were event-free, while this was 62% for non-classical/silent ≥ 45 years, 60% for classical < 45 years, and 80% for non-classical/silent < 45 years.

CONCLUSIONS

CREs occurred in almost half of CD patients during follow-up, with functional disorders being very common. New follow-up strategies for adult CD may be developed based on age and clinical pattern at diagnosis.

Persistent symptoms are diverse and associated with health concerns and impaired quality of life in patients with paediatric coeliac disease diagnosis after transition to adulthood

Objective

To investigate the prevalence and associated factors of persistent symptoms despite a strict gluten-free diet in adult patients with coeliac disease diagnosed in childhood.

Design

Medical data on 239 currently adult patients with paediatric diagnosis were collected from patient records. Also, patients completed structured study questionnaire. All variables were compared between those with and without persistent symptoms.

Results

Altogether 180 patients reported adhering to a strict gluten-free diet. Of these, 18% experienced persistent symptoms, including various gastrointestinal symptoms (73%), arthralgia (39%), fatigue (39%), skin symptoms (12%) and depression (6%). Those reporting persistent symptoms had more often gastrointestinal comorbidities (19% vs 6%, p=0.023), health concerns (30% vs 12%, p=0.006) and experiences of restrictions on daily life (64% vs 43%, p=0.028) than the asymptomatic subjects. The patients with symptoms had poorer general health (median score 13 vs 14, p=0.040) and vitality (15 vs 18, p=0.015) based on a validated Psychological General Well-Being Questionnaire and more severe symptoms on a Gastrointestinal Symptom Rating Scale scale (total score 2.1 vs 1.7, p<0.001). Except for general health, these differences remained significant after adjusting for comorbidities. The groups were comparable in current sociodemographic characteristics. Furthermore, none of the childhood features, including clinical, serological and histological presentation at diagnosis, and adherence and response to the diet after 6–24 months predicted symptom persistence in adulthood.

Conclusion

Almost one-fifth of adult patients diagnosed in childhood reported persistent symptoms despite a strict gluten-free diet. The ongoing symptoms were associated with health concerns and impaired quality of life.

Adherence to Gluten-Free Diet Restores Alpha Diversity in Celiac People but the Microbiome Composition Is Different to Healthy People

Celiac disease (CD) is an autoimmune disease with the destruction of small intestinal villi, which occurs in genetically predisposed individuals. At the present moment, a gluten-free diet (GFD) is the only way to restore the functionality of gut mucosa. However, there is an open debate on the effects of long-term supplementation through a GFD, because some authors report an unbalance in microbial taxa composition. Methods: For microbiome analysis, fecal specimens were collected from 46 CD individuals in GFD for at least 2 years and 30 specimens from the healthy controls (HC). Data were analyzed using an ensemble of software packages: QIIME2, Coda-lasso, Clr-lasso, Selbal, PICRUSt2, ALDEx2, dissimilarity-overlap analysis, and dysbiosis detection tests. Results: The adherence to GFD restored the alpha biodiversity of the gut microbiota in celiac people but microbial composition at beta diversity resulted as different to HC. The microbial composition of the CD subjects was decreased in a number of taxa, namely Bifidobacterium longum and several belonging to Lachnospiraceae family, whereas Bacteroides genus was found to be more abundant. Predicted metabolic pathways among the CD bacterial communities revealed an important role in tetrapyrrole biosynthesis. Conclusions: CD patients in GFD had a non-dysbiotic microbial composition for the crude alpha diversity metrics. We found significant differences in beta diversity, in certain taxon, and pathways between subjects with inactive CD in GFD and controls. Collectively, our data may suggest the development of new GFD products by modulating the gut microbiota through diet, supplements of vitamins, and the addition of specific prebiotics.

Association between iron supplementation and the presence of diarrhoea in Peruvian children aged 6-59 months: analysis of the database of the Demographic and Family Health Survey in Peru (DHS, Peru), years 2009-2019

INTRODUCTION

According to the WHO, anaemia is a severe public health problem when the prevalence is ≥ 40 %. In 2019, in Peru, 40·1 % of children (aged 6 to 35 months) are diagnosed as anaemic. This is a concern since, despite the efforts of the governments to reduce the prevalence, the problem has stagnated since 2011. The treatment applied to deal with anaemia is Fe supplementation. Although Fe is essential for cell function, an excess can produce adverse responses, such as gut inflammation affecting microbiota and resulting in diarrhoeic episodes.

OBJECTIVE

To determine the association between diarrhoea and Fe supplementation in children with and without anaemia, controlling for different socio-demographic variables.

DESIGN

We conducted via logistic regression to obtain diarrhoea prevalence ratios (PR), adjusted by age, sex, geographic region, water and sanitation service, and rurality. The survey asked for recent episodes of diarrhoea during the last 7 d; similarly, after the consumption of Fe supplements during the last 12 months before the survey.

SETTING

Peru.

PARTICIPANTS

The Demographic and Family Health Survey (DHS) is conducted annually at home among 14 202 children on average (2009-2019).

RESULTS

Fe supplementation in the last 7 d (PR = 1·09) or the last 12 months (PR = 1·19) (P < 0·0001) was associated with an increased risk of diarrhoea. The same association was observed between Fe supplementation and the presence of anaemia.

CONCLUSIONS

Fe supplementation is associated with diarrhoea and overuse in children should be avoided.

Manipulation of the gut microbiome in gluten-intolerance

PURPOSE OF REVIEW

Gluten is a complex mixture of highly immunogenic glutamine- and proline-rich proteins found in some cereals. In celiac disease (CeD), gluten triggers an autoimmune response due to its interaction with the human leukocyte antigen heterodimers that confer the genetic risk. The involvement of gluten in other disorders has also been investigated, but its role beyond CeD is still unclear. Here, we review the most recent evidence of the involvement of gluten in diseases and the opportunities of manipulating the gut microbiota to treat or prevent gluten-related conditions.

RECENT FINDINGS

Most of the new studies have been conducted in the context of CeD, where important evidence has been gained on associations between the gut microbiota, genotype, and environmental factors such as breastfeeding and antibiotics. The role of the microbiota has been investigated in several prospective, observational and interventional studies with probiotics, which together showed that the gut microbiota could be targeted to ameliorate and aid in the prevention of CeD development.

SUMMARY

Several studies have evidenced how genetic and environmental factors influence the gut microbiome with consequences in CeD. These findings could inspire the development of microbiota modulation strategies to support the prevention or treatment of CeD.