Gastrointestinal Microbiome and Multiple Health Outcomes: Umbrella Review

Serum neurofilament light chain in response to probiotics in bi-center, double-blind, randomized, placebo-controlled clinical trial (CleverAge Biota)

BACKGROUND AND AIMS

Neurodegenerative disorders affecting the brain and spinal cord are caused by a large number of factors. More recently, imbalances in gut microbiota are found to be one factor linked directly to neurological dysfunction. Probiotics prevent cognitive decline. For the first time, the effect of probiotics was assessed by monitoring the concentrations of the neurodegeneration biomarker neurofilament light chains (NfL) in a well-defined group of community-dwelling individuals. The aim of this study was to determine whether administration of our new probiotics could reduce NfL concentrations.

METHODS

The serum NfL concentrations were measured in total of 190 serum samples of 85 older community-dwelling individuals. The participants were randomly divided into two groups: the PROPLA group and the PLAPRO group. Individuals in the PROPLA group started with a three-month use of probiotics and continued with a three-month use of placebo while the order was reversed in the PLAPRO group. The participants underwent detailed examinations at three time points: at baseline, in three and six months. The serum NfL concentrations were determined using ultrasensitive single-molecule array (SIMOA) assay.

RESULTS

Longitudinal comparisons of NfL concentrations between samplings at different time points in the PROPLA and PLAPRO groups showed no statistically significant differences. Baseline NfL concentrations at the beginning of the study and in the succeeding samplings were not significantly different for the two groups in cross-sectional comparisons.

CONCLUSIONS

Serum NfL concentrations were not influenced by the three-month use of probiotics.

Effects of Enterococcus faecium Extracellular Vesicles on Intestinal Barrier Function and Microbiota in Piglets

Enterococcus faecium (Ef) is a common microorganism in the gastrointestinal tract, recognized for its beneficial effects on human and animal health. It plays a vital role in promoting intestinal microbial balance and enhancing gut barrier function. A key feature of Ef extracellular vesicles (EfEVs) is their ability to specifically target sites within the intestine, leading us to hypothesize that EfEVs function as an important active component of Ef in intestinal microenvironment regulation. This study aimed to explore the impact of EfEV supplementation on the intestinal barrier function and microbiota composition in piglets. In vitro intestinal porcine epithelial cell J2 (IPEC-J2) cell culture experiments have shown that supplementation with EfEV significantly enhanced cell viability, increased the activity of the antioxidant enzyme, promoted cell proliferation, and inhibited autophagy. In vitro, fecal culture experiments demonstrated significant increases in OD630 and the contents of acetic aid, butyric acid, and isovaleric acid, and decreases in valeric acid following EfEV supplementation. Furthermore, EfEV supplementation altered the diversity and composition of the intestinal microbiota. It significantly reduced levels of Escherichia-Shigella at the family level, while increasing the abundance of beneficial microorganisms, including [Eubacterium]_eligens_group, unidentified_Mitochondria, Lachnoclostridium. In conclusion, EfEV plays a pivotal role in inhibiting pathogens growth, enhancing the production of metabolites such as acetic acid and butyrate acid, providing energy for microorganisms, and protecting the intestinal barrier.

Is the oral pathogen, Porphyromona gingivalis, associated to colorectal cancer?: a systematic review

BACKGROUND

The association between the oral pathogen Porphyromonas gingivalis (PG) and the gut microbiota in colorectal cancer (CRC) patients has been explored with inconsistent results. This study aims to systematically assess this potential association.

MATERIALS AND METHODS

A systematic review was conducted across three databases (Pubmed, Embase and Web of Science) from inception up to January 2023 and updated until November 2024. Inclusion criteria were observational studies examining PG in the microbiota of adults with CRC compared to healthy controls. Exclusion criteria were studies without control group of healthy individuals, other designs or without full-text access. Two reviewers independently selected and extracted data following a pre-registered protocol. Disagreements were resolved by consensus or with a third reviewer. Risk of bias (RoB) was assessed using the Newcastle-Ottawa Scale (NOS). Results were summarized with a flow diagram, tables, and narrative descriptions. Meta-analysis was not feasible, so Fisher's method for combining p-values and the sign test were used as alternative integration methods.

RESULTS

Finally, 18 studies, with 23 analysis units were included, providing a total sample of 4,373 participants (48.0% cases and 52.0%controls), 38.2% men and 61.8% women, with a similar distribution among cases and controls. The mean (SD) age of cases was 63.3 (4.382) years old and 57.0 (7.753) years for controls. Most of the studies analyzed the presence of PG in feces (70.0%) collected before colonoscopy (55.0%) and were classified with good quality (70.0%) in the RoB assessment. Results suggested an effect (Fisher's test, p = .000006) with some evidence towards a positive association of PG in CRC patients compared to healthy controls (Sign test, p = .039).

CONCLUSIONS

Results of the systematic review suggest that PG is associated with the microbiota of CRC patients. Lack of information to calculate the effect size prevented the performance of a meta-analysis. Future research should aim for standardized protocols and statistical approaches.

FUNDING

No funding was received for this work.

SYSTEMATIC REVIEW REGISTRATION

The research protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 2023 (registration number: CRD42023399382).

Opioid Use and Gut Dysbiosis in Cancer Pain Patients

Opioids are commonly used for the management of severe chronic cancer pain. Their well-known pharmacological effects on the gastrointestinal system, particularly opioid-induced constipation (OIC), are the most common limiting factors in the optimization of analgesia, and have led to the wide use of laxatives and/or peripherally acting mu-opioid receptor antagonists (PAMORAs). A growing interest has been recently recorded in the possible effects of opioid treatment on the gut microbiota. Preclinical and clinical data, as presented in this review, showed that alterations of the gut microbiota play a role in modulating opioid-mediated analgesia and tolerability, including constipation. Moreover, due to the bidirectional crosstalk between gut bacteria and the central nervous system, gut dysbiosis may be crucial in modulating opioid reward and addictive behavior. The microbiota may also modulate pain regulation and tolerance, by activating microglial cells and inducing the release of inflammatory cytokines and chemokines, which sustain neuroinflammation. In the subset of cancer patients, the clinical meaning of opioid-induced gut dysbiosis, particularly its possible interference with the efficacy of chemotherapy and immunotherapy, is still unclear. Gut dysbiosis could be a new target for treatment in cancer patients. Restoring the physiological amount of specific gut bacteria may represent a promising therapeutic option for managing gastrointestinal symptoms and optimizing analgesia for cancer patients using opioids.

Effects of probiotics, prebiotics and synbiotics on anthropometric, cardiometabolic and inflammatory markers: An umbrella review of meta-analyses

BACKGROUND & AIMS

Though probiotics, prebiotics and synbiotics have been shown to confer health benefits, their effects on cardiometabolic risk factors remain unclear. Therefore, we conducted an umbrella review to examine their effectiveness on anthropometric, cardiometabolic and inflammatory markers.

METHODS

We conducted an umbrella review on eligible systematic reviews with meta-analysis (SRMA) published from journals' inception till 13 January 2023 retrieved from seven electronic databases (CINAHL, EMBASE, ProQuest, PubMed, Scopus, The Cochrane Library, and Web of Science). Methodological quality was appraised using the Assessment of Multiple Systematic Reviews 2 (AMSTAR2) tool and certainty of evidence was graded into five classes. Random-effects meta-analyses were performed on outcome effect sizes at the SRMA and primary study levels. Extent of overlapping articles were evaluated using corrected cover area.

RESULTS

24 systematic reviews representing 265 unique studies, 1076 unique effect sizes and 25,973 subjects were included. Synbiotics were evidently more effective in improving weight (-1.91 kg, 95%CI -3.45 kg to -0.37 kg, p = 0.02), total cholesterol (-12.17 mg/dl, 95%CI -17.89 mg/dl to -6.46 mg/dl, p < 0.001), low-density lipoprotein (-12.26 mg/dl, 95%CI -18.27 mg/dl to -6.25 mg/dl, p < 0.01), waist circumference (-1.85 cm, 95%CI -2.77 cm to -0.94 cm, p < 0.01), and fasting plasma glucose (-9.68 mg/dl, 95%CI -16.18 mg/dl to -3.18 mg/dl, p < 0.01). Prebiotics were more effective in improving body mass index (-0.34 kg/m2, 95%CI -0.48 kg/m2 to -0.20 kg/m2, p < 0.01), and HOMA-IR (-0.92, 95%CI -1.91 to 0.07, p = 0.06). Probiotics were shown to be more effective in reducing diastolic blood pressure (-1.34 mmHg, 95%CI -2.14 mmHg to -0.55 mmHg, P < 0.01) improving insulin level change (-0.84 mIU/mL, 95%CI -1.27 mIU/mL to -0.41 mIU/mL, p < 0.01), and the percentage of body fat (-0.66%, 95%CI -0.70% to -0.61%, p < 0.01). For all outcomes, the credibility of evidence was classified as class IV.

CONCLUSION

Pre-, pro-, and synbiotics can significantly enhance anthropometric indices, glucose and lipid profiles, blood pressure, and inflammatory markers in individuals confronting obesity. While suggesting their supplementation holds promise for this population, the true clinical impact hinges on tailoring these interventions to specific indications and customizing treatment strategies to align with individual patient needs.

The Potential Impact of Probiotics on Human Health: An Update on Their Health-Promoting Properties

Probiotics, known to be live microorganisms, have been shown to improve or restore the gut microbiota, which in turn has been linked to improved health. It is believed that probiotics are the modern equivalent of a panacea, with claims that they may treat or prevent different diseases both in children and adults (e.g., from colic in babies to cardiovascular disease, respiratory infection, and cancer in adults). Ever since the early 2000s, probiotic-based fermented foods have had a resurgence in popularity, mostly due to claims made regarding their health benefits. Fermented foods have been associated with the prevention of irritable bowel syndrome, lactose intolerance, gastroenteritis, and obesity, but also other conditions such as chronic diarrhea, allergies, dermatitis, and bacterial and viral infections, all of which are closely related to an unhealthy lifestyle. Recent and ongoing developments in microbiome/microbiota science have given us new research directions for probiotics. The new types, mechanisms, and applications studied so far, and those currently under study, have a great potential to change scientific understanding of probiotics' nutritional applications and human health care. The expansion of fields related to the study of the microbiome and the involvement of probiotics in its improvement foreshadow an era of significant changes. An expanding range of candidate probiotic species is emerging that can address newly elucidated data-driven microbial niches and host targets. In the probiotic field, new variants of microbiome-modulating interventions are being developed, including prebiotics, symbiotics, postbiotics, microbial consortia, live biotherapeutic products, and genetically modified organisms, with renewed interest in polyphenols, fibers, and fermented foods to ensure human health. This manuscript aims to analyze recent, emerging, and anticipated trends in probiotics (sources, doses, mechanism of action, diseases for which probiotics are administered, side effects, and risks) and create a vision for the development of related areas of influence in the field.

Effect of probiotics or prebiotics on thyroid function: A meta-analysis of eight randomized controlled trials

BACKGROUND

Microbiome-directed therapies are increasingly utilized to optimize thyroid function in both healthy individuals and those with thyroid disorders. However, recent doubts have been raised regarding the efficacy of probiotics, prebiotics, and synbiotics in improving thyroid function. This systematic review aimed to investigate the potential relationship between probiotics/prebiotics and thyroid function by analyzing the impact on thyroid hormone levels.

METHODS

We conducted a comprehensive systematic review and meta-analysis of randomized controlled trials that investigated the effects of probiotics, prebiotics, and synbiotics on free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and thyroid stimulating hormone receptor antibody (TRAb) levels. We searched for articles from PubMed, Scopus, Web of Science, and Embase up until April 1st, 2023, without any language restriction. Quantitative data analysis was performed using a random-effects model, with standardized mean difference (SMD) and 95% confidence interval as summary statistics. The methods and results were reported according to the PRISMA2020 statement.

RESULTS

A total of eight articles were included in this review. The meta-analysis showed no significant alterations in TSH (SMD: -0.01, 95% CI: -0.21, 0.20, P = 0.93; I2: 0.00%), fT4 (SMD: 0.04, 95% CI: -0.29, 0.21, P = 0.73; I2: 0.00%) or fT3 (SMD: 0.45, 95% CI: -0.14, 1.03, P = 0.43; I2: 78.00%), while a significant reduction in TRAb levels was observed (SMD: -0.85, 95% CI: -1.54, -0.15, P = 0.02; I2: 18.00%) following probiotics/prebiotics supplementation. No indication of publication bias was found.

CONCLUSIONS

Probiotics/prebiotics supplementation does not influence thyroid hormone levels, but may modestly reduce TRAb levels in patients with Graves' disease.

Gut microbial dysbiosis in patients with Cushing's disease in long-term remission. Relationship with cardiometabolic risk

Background

Patients with Cushing's disease (CD) in remission maintain an increased cardiovascular risk. Impaired characteristics of gut microbiome (dysbiosis) have been associated with several cardiometabolic risk factors.

Methods

Twenty-eight female non-diabetic patients with CD in remission with a mean ± SD) age of 51 ± 9 years, mean ( ± SD) BMI, 26 ± 4, median (IQR) duration of remission, 11(4) years and 24 gender-, age, BMI-matched controls were included. The V4 region of the bacterial 16S rDNA was PCR amplified and sequenced to analyse microbial alpha diversity (Chao 1 index, observed number of species, Shannon index) and beta diversity analysis through the Principal Coordinates Analysis (PCoA) of weighted and unweighted UniFrac distances. Inter-group difference in microbiome composition was analysed using MaAsLin2.

Results

The Chao 1 index was lower in CD as compared with controls (Kruskal-Wallis test, q = 0.002), indicating lower microbial richness in the former. Beta diversity analysis showed that faecal samples from CS patients clustered together and separated from the controls (Adonis test, p<0.05). Collinsella, a genus form of the Actinobacteria phylum was present in CD patients only, whereas Sutterella, a genus from Proteobacteria phylum, was scarcely detectable/undetectable in CD patients as well as Lachnospira, a genus of the Lachnospiraceae family of the Firmicutes phylum. In CS, the Chao 1 index was associated with fibrinogen levels and inversely correlated with both triglyceride concentrations and the HOMA-IR index (p<0.05).

Conclusions

Patients with CS in remission have gut microbial dysbiosis which may be one of the mechanisms whereby cardiometabolic dysfunctions persist after "cure".

Diarrhea accompanies intestinal inflammation and intestinal mucosal microbiota dysbiosis during fatigue combined with a high-fat diet

OBJECTIVE

It was reported fatigue or a high-fat diet triggers diarrhea, and intestinal microbiota may play central roles in diarrhea. Therefore, we investigated the association between the intestinal mucosal microbiota and the intestinal mucosal barrier from fatigue combined with a high-fat diet.

METHOD

This study divided the Specific pathogen-free (SPF) male mice into the normal group (MCN) and the standing united lard group (MSLD). The MSLD group stood on water environment platform box for 4 h/day for 14 days, and 0.4 mL lard was gavaged from day 8, twice daily for 7 days.

RESULT

After 14 days, Mice in the MSLD group showed diarrhea symptoms. The pathological analysis showed structural damage to the small intestine in the MSLD group, with an increasing trend of interleukin-6 (IL-6) and IL-17, and inflammation accompanied by structural damage to the intestine. Fatigue combined with a high-fat diet considerably decreased Limosilactobacillus vaginalis and Limosilactobacillus reuteri, and among them, Limosilactobacillus reuteri positively associated with Muc2 and negatively with IL-6.

CONCLUSION

The interactions between Limosilactobacillus reuteri and intestinal inflammation might be involved in the process of intestinal mucosal barrier impairment in fatigue combined with high-fat diet-induced diarrhea.

Potential Benefits of Anthocyanins in Chronic Disorders of the Central Nervous System

Anthocyanins have been shown to be effective in chronic diseases because of their antioxidant and anti-inflammatory effects together with changes in the gut microbiota and modulation of neuropeptides such as insulin-like growth factor-1. This review will examine whether these mechanisms may be effective to moderate the symptoms of disorders of the central nervous system in humans, including schizophrenia, Parkinson's disease, Alzheimer's disease, autism spectrum disorder, depression, anxiety, attention-deficit hyperactivity disorder and epilepsy. Thus, anthocyanins from fruits and berries should be considered as complementary interventions to improve these chronic disorders.