Therapeutic Advances in Gut Microbiome Modulation in Patients with Inflammatory Bowel Disease from Pediatrics to Adulthood

Physicians' Explanatory Models of Pediatric Inflammatory Bowel Disease: A Qualitative Interview Study

Explanatory models are culturally informed representations of illness that convey understandings of the etiology and expected course of disease. Substantial research has explored lay explanatory models, but examining physicians' clinical explanatory models can also provide insight into patients' understandings of illness because physicians are a foundational source of authoritative knowledge that shapes lay concepts of illness and disease. This study characterized the explanatory models used by pediatric gastroenterologists when explaining inflammatory bowel disease (IBD) to children. We conducted semi-structured qualitative interviews with 20 pediatric gastroenterologists across the United States about their clinical communication and explanatory models. We identified two primary explanatory models used to describe immune dysregulation in pediatric IBD: the defense and protection model, which characterizes the immune system as an army that erroneously sees the body as "non-self" and attacks it; and the switch model, which conceptualizes treatment as activating a switch that turns off a faulty immune response. We also identified two models used by some physicians to describe inflammation: the scratch and scrape model, which compares IBD inflammation to scratches or scrapes on the skin; and the bonfire model, which compares inflammation to a fire in need of extinguishing. While the use of militaristic metaphors is pervasive in medicine, describing autoimmunity as a battle against the self may lead children to perceive their body as the enemy. This may be compounded by describing the immune system as "confused" while noting its ongoing protective function. Use of these explanatory models may nevertheless improve patient disease-related knowledge.

Prediction of Response to Systemic Corticosteroids in Active UC by Microbial Composition-A Prospective Multicenter Study

BACKGROUND

Corticosteroids are used for induction of remission in patients with moderately to severely active ulcerative colitis. However, up to one-third of patients fail to this therapy. We investigated if fecal microbial composition or its metabolic capacity are associated with response to systemic corticosteroids.

METHODS

In this prospective, multicenter study, patients with active ulcerative colitis (Lichtiger score ≥4) receiving systemic corticosteroids were eligible. Data were assessed and fecal samples collected before and after 4 weeks of treatment. Patients were divided into responders (decrease of Lichtiger Score ≥50%) and nonresponders. The fecal microbiome was assessed by the 16S rRNA gene marker and analyzed with QIIME 2. Microbial metabolic pathways were predicted using parsimonious flux balance analysis.

RESULTS

Among 93 included patients, 69 (74%) patients responded to corticosteroids after 4 weeks. At baseline, responders could not be distinguished from nonresponders by microbial diversity and composition, except for a subgroup of biologic-naïve patients. Within 4 weeks of treatment, responders experienced changes in beta diversity with enrichment of ascribed beneficial taxa, including Blautia, Anaerostipes, and Bifidobacterium, as well as an increase in predicted butyrate synthesis. Nonresponders had only minor longitudinal taxonomic changes with a significant increase of Streptococcus salivarius and a microbial composition shifting away from responders.

CONCLUSION

Baseline microbial diversity and composition seem to be of limited use to predict response to systemic corticosteroids in active ulcerative colitis. Response is longitudinally associated with restoration of microbial composition and its metabolic capacity.

The microbiome landscape in pediatric Crohn's disease and therapeutic implications

Dysbiosis of the gut microbiome and a pathological immune response in intestinal tissues form the basis of Crohn's disease (CD), which is a debilitating disease with relevant morbidity and mortality. It is increasing in childhood and adolescents, due to western life-style and nutrition and a large set of predisposing genetic factors. Crohn's disease-associated genetic mutations play an essential role in killing pathogens, altering mucosal barrier function, and protecting the host microbiome, suggesting an important pathogenic link. The intestinal microbiome is highly variable and can be influenced by environmental factors. Changes in microbial composition and a reduction in species diversity have been shown to be central features of disease progression and are therefore the target of therapeutic approaches. In this review, we summarize the current literature on the role of the gut microbiome in childhood, adolescent, and adult CD, current therapeutic options, and their impact on the microbiome.

Roles of Short-Chain Fatty Acids in Inflammatory Bowel Disease

The gut microbiome is a diverse bacterial community in the human gastrointestinal tract that plays important roles in a variety of biological processes. Short-chain fatty acids (SCFA) are produced through fermentation of dietary fiber. Certain microbes in the gut are responsible for producing SCFAs such as acetate, propionate and butyrate. An imbalance in gut microbiome diversity can lead to metabolic disorders and inflammation-related diseases. Changes in SCFA levels and associated microbiota were observed in IBD, suggesting an association between SCFAs and disease. The gut microbiota and SCFAs affect reactive oxygen species (ROS) associated with IBD. Gut microbes and SCFAs are closely related to IBD, and it is important to study them further.

Early Life Oral Antibiotics Are Associated With Pediatric-Onset Inflammatory Bowel Disease-A Nationwide Study

OBJECTIVES

Early-life environmental triggers are thought to play a larger role in pediatric-onset inflammatory bowel disease (pIBD) compared to adult-onset IBD. We aimed to assess the risk of developing pIBD after exposure to oral antibiotics during the first 5 years of life.

METHODS

In a nation-wide cohort study, we identified all patients diagnosed with pIBD (<18 years at diagnosis) in Denmark between 1995 and 2018 from the National Patient Registry and matched them with up to 10 reference individuals. Antibiotic exposure was defined as being prescribed antibiotics during first 5 years of life. Data were retrieved from the National Prescription Register. Outcome was developing pIBD. Risk estimates are presented by hazard ratios (HR) with 95% confidence intervals (CI).

RESULTS

We identified 1927 pIBD patients and 18,318 reference individuals. Oral antibiotic exposure during the first 5 years of life was associated with a higher risk of developing pIBD (HR = 1.33 [95% CI: 1.2-1.5], P <0.0001). The risk was also increased if patients had ≥4 antibiotic prescriptions compared to no antibiotics (HR = 1.33 [95% CI: 1.2-1.5], P <0.0001). Broad-spectrum antibiotics increased the risk of pIBD compared to narrow-spectrum antibiotics (HR = 1.29 [95% CI: 1.2-1.4], P < 0.0001). When stratified by IBD subtypes, only Crohn disease was significantly associated with exposure to antibiotics (HR = 1.37 [95% CI: 1.1-1.7], P = 0.002).

CONCLUSIONS

In this nationwide registry-based study, we found that oral antibiotic exposure during first 5 years of life was associated with an increased risk of pIBD. Repeated antibiotic exposures increased risk estimates.

Updated immunomodulatory roles of gut flora and microRNAs in inflammatory bowel diseases

Inflammatory bowel disease is a heterogeneous intestinal inflammatory disorder, including ulcerative colitis (UC) and Crohn's disease (CD). Existing studies have shown that the pathogenesis of IBD is closely related to the host's genetic susceptibility, intestinal flora disturbance and mucosal immune abnormalities, etc. It is generally believed that there are complicated interactions between host immunity and intestinal microflora/microRNAs during the occurrence and progression of IBD. Intestinal flora is mainly composed of bacteria, fungi, viruses and helminths. These commensals are highly implicated in the maintenance of intestinal microenvironment homeostasis alone or in combination. MiRNA is an endogenous non-coding small RNA with a length of 20 to 22 nucleotides, which can perform a variety of biological functions by silencing or activating target genes through complementary pairing bonds. A large quantity of miRNAs are involved in intestinal inflammation, mucosal barrier integrity, autophagy, vesicle transportation and other small RNA alterations in IBD circumstance. In this review, the immunomodulatory roles of gut flora and microRNAs are updated in the occurrence and progression of IBD. Meanwhile, the gut flora and microRNA targeted therapeutic strategies as well as other immunomodulatory approaches including TNF-α monoclonal antibodies are also emphasized in the treatment of IBD.

The Association of Antibiotic Exposure with New-Onset Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

INTRODUCTION

The role of antibiotics in the development of inflammatory bowel disease (IBD) remains controversial, primarily due to conflicting data from individual studies. We conduct a systematic review and meta-analysis to study the effect of antibiotic exposure on IBD development.

METHODOLOGY

The MEDLINE and Cochrane CENTRAL databases were queried from their inception to April 2021 for published articles studying the association between antibiotic exposure and new-onset IBD. Our analysis was stratified by timing of antibiotic exposure - exposure in childhood and any lifetime exposure. Adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs) from each study were pooled using a random-effects model.

RESULTS

10 case-control studies and 2 cohort studies (N=29,880 IBD patients and N=715,548 controls) were included. Patients with Crohn's Disease (CD), compared with controls, were associated significantly with antibiotic exposure in childhood and any lifetime exposure to antibiotics (OR 1.52 [1.23-1.87]; p<0.00001). Patients with Ulcerative Colitis (UC), compared with controls, reported non-significant association with antibiotic exposure in childhood and any lifetime exposure. (OR 1.11 [0.93-1.33]; p=0.25) CONCLUSION: This meta-analysis suggests that exposure to antibiotics significantly increases the odds of developing CD and IBD in general. These findings re-emphasize the importance of cautious and judicious use of antibiotics.

Harnessing the Power of Precision Medicine and Novel Biomarkers to Treat Crohn’s Disease

Crohn’s disease (CD) is a chronic inflammatory condition that affects the gastrointestinal tract. It is part of a spectrum of inflammatory Bowel Diseases (IBD). The disease is complex, characterized by significant inter and intra-individual heterogeneity, which contributes to a diverse and multifaceted portrayal of the disease. Consequently, applying specific and accurate treatment is challenging, and therapeutic success rates remain disappointing and insufficient. In recent years, significant advances in the therapeutic potential of CD have been made. Hope has been provided by these developments in the form of an expanding treatment toolkit. However, even with these beneficial adjustments, patients are frequently treated using an ineffective “one size fits all” treatment protocol, ultimately leading to a plateau in drug effectiveness and a decline in overall treatment success rates. Furthermore, with the advancement in the genome-wide association study, in combination with significant bioinformatic developments, the world of medicine has moved in the direction of personalized, tailored-treatment medicine, and this trend has not escaped the world of IBDs. Prediction models, novel biomarkers, and complex algorithms are emerging and inspiring optimism that CD patients will be treated with “precision medicine” in the near future, meaning that their treatments will be selected based on the patient’s various unique features. In this review, we will outline the current diagnostic and therapeutic limitations that lead to a glass ceiling effect and thus send us in pursuit of discovering novel biomarkers. We will illustrate the challenges and difficulties in discovering relevant and innovative biomarkers and implementing them into everyday clinical practice. We will also heighten the progress made in practicing personalized medicine for CD patients and shed light on future directions and horizons.

Dietary fungi in cancer immunotherapy: From the perspective of gut microbiota

Immunotherapies are recently emerged as a new strategy in treating various kinds of cancers which are insensitive to standard therapies, while the clinical application of immunotherapy is largely compromised by the low efficiency and serious side effects. Gut microbiota has been shown critical for the development of different cancer types, and the potential of gut microbiota manipulation through direct implantation or antibiotic-based depletion in regulating the overall efficacy of cancer immunotherapies has also been evaluated. However, the role of dietary supplementations, especially fungal products, in gut microbiota regulation and the enhancement of cancer immunotherapy remains elusive. In the present review, we comprehensively illustrated the limitations of current cancer immunotherapies, the biological functions as well as underlying mechanisms of gut microbiota manipulation in regulating cancer immunotherapies, and the benefits of dietary fungal supplementation in promoting cancer immunotherapies through gut microbiota modulation.

Current evidence and clinical relevance of drug-microbiota interactions in inflammatory bowel disease

Background

Inflammatory bowel disease (IBD) is a chronic relapsing-remitting disease. An adverse immune reaction toward the intestinal microbiota is involved in the pathophysiology and microbial perturbations are associated with IBD in general and with flares specifically. Although medical drugs are the cornerstone of current treatment, responses vary widely between patients and drugs. The intestinal microbiota can metabolize medical drugs, which may influence IBD drug (non-)response and side effects. Conversely, several drugs can impact the intestinal microbiota and thereby host effects. This review provides a comprehensive overview of current evidence on bidirectional interactions between the microbiota and relevant IBD drugs (pharmacomicrobiomics).

Methods

Electronic literature searches were conducted in PubMed, Web of Science and Cochrane databases to identify relevant publications. Studies reporting on microbiota composition and/or drug metabolism were included.

Results

The intestinal microbiota can both enzymatically activate IBD pro-drugs (e.g., in case of thiopurines), but also inactivate certain drugs (e.g., mesalazine by acetylation via N-acetyltransferase 1 and infliximab via IgG-degrading enzymes). Aminosalicylates, corticosteroids, thiopurines, calcineurin inhibitors, anti-tumor necrosis factor biologicals and tofacitinib were all reported to alter the intestinal microbiota composition, including changes in microbial diversity and/or relative abundances of various microbial taxa.

Conclusion

Various lines of evidence have shown the ability of the intestinal microbiota to interfere with IBD drugs and vice versa. These interactions can influence treatment response, but well-designed clinical studies and combined in vivo and ex vivo models are needed to achieve consistent findings and evaluate clinical relevance.

The gut microbiome in human health and disease-Where are we and where are we going? A bibliometric analysis

Background

There are trillions of microbiota in our intestinal tract, and they play a significant role in health and disease via interacting with the host in metabolic, immune, neural, and endocrine pathways. Over the past decades, numerous studies have been published in the field of gut microbiome and disease. Although there are narrative reviews of gut microbiome and certain diseases, the whole field is lack of systematic and quantitative analysis. Therefore, we outline research status of the gut microbiome and disease, and present insights into developments and characteristics of this field to provide a holistic grasp and future research directions.

Methods

An advanced search was carried out in the Web of Science Core Collection (WoSCC), basing on the term "gut microbiome" and its synonyms. The current status and developing trends of this scientific domain were evaluated by bibliometric methodology. CiteSpace was used to perform collaboration network analysis, co-citation analysis and citation burst detection.

Results

A total of 29,870 articles and 13,311 reviews were retrieved from the database, which involve 42,900 keywords, 176 countries/regions, 19,065 institutions, 147,225 authors and 4,251 journals. The gut microbiome and disease research is active and has received increasing attention. Co-cited reference analysis revealed the landmark articles in the field. The United States had the largest number of publications and close cooperation with other countries. The current research mainly focuses on gastrointestinal diseases, such as inflammatory bowel disease (IBD), ulcerative colitis (UC) and Crohn's disease (CD), while extra-intestinal diseases are also rising, such as obesity, diabetes, cardiovascular disease, Alzheimer's disease, Parkinson's disease. Omics technologies, fecal microbiota transplantation (FMT) and metabolites linked to mechanism would be more concerned in the future.

Conclusion

The gut microbiome and disease has been a booming field of research, and the trend is expected to continue. Overall, this research field shows a multitude of challenges and great opportunities.

Microbiome engineering: engineered live biotherapeutic products for treating human disease

The human microbiota is implicated in many disease states, including neurological disorders, cancer, and inflammatory diseases. This potentially huge impact on human health has prompted the development of microbiome engineering methods, which attempt to adapt the composition and function of the human host-microbiota system for a therapeutic purpose. One promising method is the use of engineered microorganisms that have been modified to perform a therapeutic function. The majority of these products have only been demonstrated in laboratory models; however, in recent years more concepts have reached the translational stage. This has led to an increase in the number of clinical trials, which are designed to assess the safety and efficacy of these treatments in humans. Within this review, we highlight the progress of some of these microbiome engineering clinical studies, with a focus on engineered live biotherapeutic products.

Pea Albumin Attenuates Dextran Sulfate Sodium-Induced Colitis by Regulating NF-κB Signaling and the Intestinal Microbiota in Mice

BACKGROUND

Inflammatory bowel disease remains a global burden with rapidly increasing incidence and prevalence in both industrialized countries and developing countries. In this study, we prepared pea albumin from pea seeds and determined its beneficial effects being anti-inflammatory and on gut microbiota modulation in dextran sulfate sodium (DSS)-challenged mice.

METHOD

Six-week-old C57BL/6N male mice received an equivalent volume (200 μL) of sterile phosphate balanced solution, 0.375, 0.75, or 1.50 g/kg body weight (BW) of pea albumin that was subjected to 2.0% DSS for 7 days to induce colitis. On day 17 of the experiment, all mice were sacrificed after blood sample collection, and colon tissue and colon contents were collected. BW change curve, colon length, myeloperoxidase (MPO) activity, mucus staining, immunofluorescence staining of T cells and macrophages, cytokines, pro-inflammatory genes expression, nuclear factor-κB (NF-κB) and signal transducer, and activator of transcription 3 (STAT3) signaling pathways as well as 16S DNA sequence were measured.

RESULTS

Our results show that pea albumin alleviates DSS-induced BW loss, colon length shortening, enhanced MPO activity, cytokines secretion, mucus deficiency, and inflammatory cell infiltration, as well as enhanced pro-inflammatory genes expression. In addition, the overactivation of NF-κB and STAT3 following DSS exposure is attenuated by pea albumin administration. Of particular interest, pea albumin oral administration restored gut microbiota dysbiosis as evidenced by enhanced α-diversity, restored β-diversity, and promoted relative abundance of Lactobacillus and Lachnospiraceae_NK4A136_group.

CONCLUSION

Taken together, the data provided herein demonstrated that pea albumin plays a protective role in DSS-induced colitis by reducing inflammatory cell infiltration, pro-inflammatory genes expression and pro-inflammatory cytokines release, inactivation of NF-κB signal, and gut microbiota modulation.

Association between intestinal microbiome and inflammatory bowel disease: insights from bibliometric analysis

•

Intestinal microbiota has been increasingly studied in the field of IBD over the last 20 years.

•

The gut microbiome, metabolites, and their corresponding host signaling pathways are highly associated with IBD.

•

Probiotics may relieve IBD as a complementary therapy.

•

The pathogenesis and treatment strategies of IBD need to be further studied.

The gut microbiome is highly linked to inflammatory bowel disease (IBD). A total of 3890 publications related to the two terms from 2000 to 2020 were extracted from the Web of Science Core Collection to study the association from a bibliometric perspective. Publications on this topic have grown rapidly since 2008. The United States and Harvard University are the country and institution with the largest number of publications, respectively. Inflammatory Bowel Diseases is the most productive journal with 211 published articles. The most influential journal in this field is Gut with 13,359 citations. The co-citation analysis of references showed that the IBD-related topics with the highest focus are “gut microbiota,” “metagenomics,” “bacterial community,” “fecal microbiota transplantation,” “probiotics,” and “colitis-associated colorectal cancer.” Keyword cluster and keyword burst analyses showed that “gut microbiota,” “metagenomics,” and “fecal microbiota transplantation” are currently the most researched topics in the field of IBD. The literature in this field is mainly distributed between alterations of the intestinal microbiota, microbial metabolites, and related host signaling pathways. Probiotic treatment also frequently appears in literature. This bibliometric analysis can guide future research and promote the development of the field of gut microbiome and IBD.