What this research adds
Swedish biotech company, de Faire Medical AB, developed a probiotic supplement containing two Bacillus strains that preferentially metabolize ethyl alcohol. Researchers conducted a pilot study in human subjects to determine whether the supplement could reduce absorption of ingested alcohol.

Conclusions
When taken daily for one week prior to consuming an alcoholic beverage, the probiotic supplement significantly reduced blood alcohol levels by 70% compared to placebo. Probiotic supplements with ethanol-metabolizing activity may help reduce the disease burden and associated economic costs of excessive alcohol consumption.

Heavy alcohol consumption can contribute to chronic diseases of the liver, heart, pancreas, and digestive tract, yet there is wide individual variation in tolerable alcohol intake. While ethyl alcohol and its primary metabolite, acetaldehyde, can cause direct oxidative stress and inflammation, it is thought that bacterial endotoxin and impaired gut barrier function promote susceptibility to alcohol-induced organ damage. Previous studies conducted in rats showed that Lactobacillus rhamnosus, taxonomically found in the Bacilli class, significantly reduced the severity of alcoholic steatohepatitis, commonly known as fatty liver disease. This bacterial strain also significantly reduced alcohol-induced oxidative stress and inflammation in both the liver and intestine and preserved gut barrier function. These results warranted further testing in humans as potential therapy or prevention of alcoholic liver disease. 

Now, de Faire Medical AB, a Life Sciences company based in Stockholm, has developed a functional dietary supplement (“AB001”) with two bacterial species that metabolize ethyl alcohol into carbon dioxide and water. AB001 is comprised primarily of fermented rice bran as the substrate, two microbes in the Bacilli class—Bacillus subtilis and Bacillus coagulans, the amino acid L-cysteine, and dextrin. L-cysteine is a sulfur-containing, rate-limiting precursor in the synthesis of glutathione, a potent antioxidant.  Delivered in an acid-resistant capsule, the microbes pass through the stomach and temporarily colonize the upper gastrointestinal tract where they can metabolize ingested ethyl alcohol thus inhibiting absorption into the bloodstream.  A small-scale human trial conducted in Germany evaluated the extent to which a small dose of alcohol entered the bloodstream following treatment for one week each of AB001 versus placebo. The researchers also measured the effect of the supplement on breath alcohol levels and cognitive function. The study was a randomized double blind crossover design so that each subject alternately participated in experimental and control groups. 

On the day of the study, subjects were given a dose of vodka to yield 0.3 g alcohol/kg body weight. This dosage was restricted by ethical guidelines of the institutional review board granting study approval. Blood and breath alcohol measurements were taken at regular intervals following alcohol consumption. Cognitive function was evaluated using a timed number connection test, and all subjects were monitored for adverse reactions. 

The results, published in Nutrition and Metabolic Insights, showed that treatment with AB001 significantly reduced blood alcohol concentration by up to 70% compared to placebo sixty minutes following alcohol ingestion. Breath alcohol concentration was approximately 30% lower with the supplement, and there was no difference in cognitive function between the two groups. No adverse events were reported. 

Mitochondrial Toxicity

Alcohol is slowly absorbed in the stomach and rapidly absorbed by intestinal epithelial cells. It enters the bloodstream where it is metabolized predominantly by alcohol dehydrogenase, an enzyme found in the liver. Acetaldehyde, a toxic product of that reaction, has been previously shown to impair mitochondrial function and induces production of reactive oxygen species (ROS). The result is an inhibition of mitochondrial respiration, reduced cellular energy production, and sensitization of the cell to further damage. It is this vicious cycle of oxidative stress that can ultimately lead to alcoholic liver disease.  

Microbial Therapy

When taken for one week prior to ingestion, AB001 was shown to curtail absorption of alcohol in the bloodstream via direct breakdown of alcohol in the intestinal lumen. Another possible mechanism is the reduction in oxidative stress which preserves barrier function in the intestinal mucosa. The reduction in breath alcohol at 30% was significant but less considerable than in blood alcohol concentration. Absorption of ethyl alcohol by the oral mucosal may account for this difference. The study authors reported additional unpublished results of a subsequent study comparing the effects of double the dose of alcohol following a single pre-treatment dose of AB001 vs. placebo. The results showed that the single dose of AB001 still conferred significant protection against alcohol absorption, though to a lesser extent. Blood alcohol concentration was 10% lower and breath alcohol was 7% lower with AB001 vs. placebo. The authors concluded that the bacteria in the dietary supplement exert optimal effect with sufficient time and dosing to enable intestinal colonization.

The authors disclosed that the study was funded by DeFaire Medical AB, Stockholm, Sweden, and one of the listed authors, Johan de Faire, is founder and shareholder of de Faire Medical, AB.

What is already known on this topic
Bronchiectasis is a progressive inflammatory disease characterized by abnormal widening of the airway and diverse symptoms including heavy mucus production, diminished ability to clear mucus, chronic cough, and shortness of breath. Previous bacterial microbiome analyses have shown clinical correlations between the abundance of certain bacterial genera and exacerbation—a period of heightened inflammation in the course of the disease. However, longitudinal studies have not shown significant changes in bacterial communities associated with exacerbation.

What this research adds
Researchers used a novel Integrative Microbiomics tool to merge bacteriome, virome, and mycobiome data from airways of bronchiectasis patients to capture more authentic in vivo dynamics among microbial communities. They further incorporated longitudinal samples to study patterns associated with exacerbation and resolution. Contrary to the previous bacterial microbiome studies, patients with higher rates of exacerbation showed significantly lower abundance of the bacterial genus, Pseudomonas, and further exhibited exclusionary interactions toward other microbes.

Conclusion

The Integrative Microbiomics tool utilizes a multi-biome approach to offer more robust pattern discovery and a view of the interactome—how the bacterial, fungal, and viral microbial groups influence one another. It could potentially delineate subtypes of bronchiectasis and other heterogeneous respiratory diseases to create more coherent exacerbation risk and treatment response prediction models.

A study published in Nature Medicine revealed that microbial interactions, rather than the presence, absence, or relative abundance of certain genera, are associated with bronchiectasis exacerbation.

Bronchiectasis is a progressive inflammatory disease characterized by abnormal widening of the airway and diverse symptoms including heavy mucus production, chronic cough, frequent respiratory tract infections, and shortness of breath. A heterogeneous etiology ranging from cystic fibrosis and pneumonia to foreign substances in the airway and unmanaged asthma make it complicated to study and treat. Previous bacterial microbiome analyses have correlated exacerbation—periods of heightened inflammation in the course of disease progression—with a less diverse airway bacterial microbiome and higher prevalence of a particular genus of gram-negative bacteria, Pseudomonas. However, longitudinal studies have not shown significant changes in bacterial communities associated with exacerbation. 

In this study, the researchers, led by Micheál Mac Aogáin and Jayanth Kumar Narayana of Lee Kong Chian School of Medicine of Nanyang Technological University in Singapore, used Integrative Microbiomics, which is available to the public as a web tool hosted by Nanyang Technological University in Singapore. It employs a computational method known as similarity network fusion (SNF) which creates networks of data for each of the available data types (e.g. bacteriome, virome, mycobiome) and then iteratively merges them and weights the data, in this case, by the relative number of taxa in each microbial biome. The tool enables exploratory data analysis called spectral clustering—a form of multivariate statistical analysis. The objective is to assemble the complex, merged dataset into a few groups, or clusters, based upon similarities in any of the parameters to discover predictor attributes for a defined outcome. 

When applied to the bronchiectasis data, the weighted SNF clearly revealed two clusters of study subjects, and those who had a higher frequency of exacerbation episodes exhibited lower airway alpha diversity, lower total numbers of microbes within the network, higher body mass index (BMI), greater use of inhaled corticosteroids, were more likely to be of European origin, and were more likely to report a history of smoking. Additionally, in contrast to the previous bacterial microbiome studies, patients with higher rates of exacerbation showed significantly lower levels of Pseudomonas abundance. Whereas forced expiratory volume test of lung function and bronchiectasis disease severity indices were not significantly different between the two clusters of study subjects, the Integrative Microbiomics tool distinguished the study subjects with more robust precision than the bacterial microbiome studies or clinical markers alone. 

Bronchiectasis Interactome

The investigators collected sputum samples from 217 patients from Scotland, Malaysia, Kuala Lumpur, and Singapore with moderate to severe bronchiectasis as well as from 40 healthy control subjects and established bacterial, viral, and fungal microbial records for each subject using 16S rRNA gene sequencing. The Interactome describes interactions among microbes which were defined as co-occurrence vs. co-exclusion. The patients who fell into the spectral cluster characterized by higher frequency of exacerbation episodes exhibited lower ecological diversity in their airway microbiomes and more negative—or exclusionary—interactions toward other microbes in the community.  

The researchers have elucidated a disrupted interactome associated with exacerbation frequency, which suggests that beyond the mere presence or absence of specific microbes, the interactions among microbes may inform clinical exacerbation. The authors theorize that antibiotic treatment of exacerbations may be disrupting the interactome rather than targeting specific bacterial organisms. 

The team conducted two separate, smaller scale studies to validate their observations. The first was a prospective cohort study with patients in Scotland to track the interactome longitudinally before, during, and after antibiotic treatment for exacerbation. This investigation supported the findings that microbial interactions were more potent predictors of time to next exacerbation than microbial abundance. The second study in collaboration with a team in Italy applied metagenomic sequencing to a separate cohort of bronchiectasis patients. Here, interactome analysis again revealed two clearly delineated clusters of patients distinguished by exacerbation frequency. The patients in the higher exacerbation frequency cluster exhibited a significantly different virome profile, including that of bacteriophages, and greater abundance of multidrug resistance genes than patients in the low frequency exacerbation cluster. This provided further support for the clinical predictive value and reproducibility of interactome analysis. 

Integrative Microbiomics

The scientists utilized a merged multi-biomics dataset that incorporated bacterial, viral, and fungal microbiome data. 

Drilling down for further detail within the high frequency exacerbation cluster, the analysis demonstrated that species in the Pseudomonas genus behaved in a significantly different manner toward other microbes than in the low frequency exacerbation cluster. 

By elucidating the interactions among the microbial taxa, the Integrative Microbiomics tool could potentially define subtypes of bronchiectasis and other respiratory diseases to create more coherent exacerbation risk prediction models and analyze interventions. This approach was able to identify the shift toward more competitive microbial relationships during periods of bronchiectasis exacerbation. This had not been previously captured by studies involving genetic sequencing to identify microbes and determine abundance. 

The authors indicated that future studies should consider competition among microbes for substrate, the influence of bacteriophages, and host immune response to shifts in the microbial interactome.

What is already known on this topic
Dry eye disease affects millions of people worldwide and is associated with ocular surface inflammation. Long-term inflammation may lead to permanent damage of the corneal epithelium. Animal models have linked two subsets of CD4+ T lymphocytes—T-helper type 17 cells (Th17) and regulatory T cells (Treg)—to chronic dry eye disease.

What this research adds
Using a daily sterile saline wash, researchers collected tears from human subjects upon first awakening and characterized the bacterial microbiome of closed-eye tears based on 16S rRNA genes. They applied statistical models and machine learning tools to differentiate the microbial communities in patients with dry eye disease and healthy subjects.

Conclusion

The analysis revealed that closed-eye tears in patients with moderate or severe dry eye disease house a distinctly different and more diverse microbiome than in healthy subjects. Through immunological interactions with Th17 cells and Treg cells, the resident ocular microbiota could potentially trigger and perpetuate inflammation in dry eye disease.

Dry eye disease affects millions of people worldwide and is associated with ocular surface inflammation. Long-term inflammation may lead to permanent damage of the corneal epithelium.  Two subsets of CD4+ T lymphocytes—T-helper type 17 cells (Th17) and regulatory T cells (Treg)—with opposing immunological roles are known to interact with resident microbiota and have been linked to chronic dry eye disease in animal studies.

Sterile saline eye washes are a proposed non-pharmaceutical treatment for patients with dry eye disease. As an adjunct to a randomized clinical trial to evaluate this treatment, a team of researchers led by Kent A. Willis, M.D. at the University of Tennessee Health Sciences Center in Memphis, collected daily closed-eye tears –those tears generated upon waking –from the study subjects. Upon enrolling in the study, subjects were evaluated for dry eye disease, stratified by level of severity, and randomly assigned to receive the saline eye wash treatment or no intervention. The researchers sequenced the bacterial microbiome of the closed eye tears using the 16S rRNA gene, and statistical analyses revealed that patients with moderate or severe dry eye disease had significantly more diverse and distinctly different microbiomes from those of normal subjects. Furthermore, the daily saline wash intervention did not significantly alter the ocular microbial communities in the treatment groups.

This study is published in Scientific Reports, a Nature Research journal. 

T-helper type 17 cells (Th17) and regulatory T cells (TREG)

Th17 cells are pro-inflammatory and produce cytokines including IL-17 to mount an immune response to pathogens. Treg cells are anti-inflammatory under normal conditions and play a role in immunologic tolerance. The ratio of these two subsets of lymphocytes modulates immune function, and an imbalance is associated with onset of several inflammatory diseases as well as autoimmunity. Previous studies have shown that resident gut microbes and their metabolites can influence this ratio. Therapies targeted at restoring optimal Th17/Treg cell balance may offer viable mechanisms to treat dry eye disease.

Bacterial Diversity

Typically, more diverse bacterial communities are considered more stable and less prone to disruption, but this research suggests that within the human eye increased microbial diversity is a marker of dry eye disease and remains largely unaffected by daily saline washes. The ecological measures of alpha diversity such as richness—the count of different taxonomic units, and evenness—the degree to which the taxonomic units are evenly distributed, revealed significant differences between subjects with dry eye disease and normal subjects. Measures of beta diversity reflected the same distinctions. The most significant distinctions in relative abundance were observed in genera including OPB56, Methylobacteriaceae, Bacteroidetes, Pseudomonas, and Meiothermus. Moreover, the daily eye rinses with sterile saline did not yield significant changes in diversity from the baseline microbiome in subjects with and without dry eye disease. The authors suggest that the mechanism to clear microbes from the eye surface is more complex than moisture level and tear clearance.

The research team utilized machine learning tools to predict with 94% accuracy which closed eye tear samples at baseline were from patients with dry eye disease. This approach has diagnostic potential.

This study demonstrated that closed-eye tears in patients with moderate or severe dry eye disease host a distinctly different and more diverse microbiome than in healthy subjects. Interactions between resident microbes and host Th17 cells and Treg cells may play a role in pathogenesis of dry eye disease. While further research is needed to determine causality, these findings present new clinical insights into the closed eye microbiome and a potential target for diagnosis and treatment of dry eye disease.

What is already known on this topic
Healthy kidneys filter the blood and rid the body of nitrogen-containing waste products such as urea, creatinine, and ammonia from normal metabolic activities. Patients with acute kidney injury or end stage kidney disease typically require dialysis, which is invasive and carries a risk of infection and other complications.

What this research adds
Researchers isolated three strains of mouse gut bacteria that work together to degrade urea and creatinine and recycle them into amino acids without a toxic buildup of ammonia. They housed the microbes in engineered microcapsules that kept the bacteria close to one another and limited access to the target nitrogenous waste products.

Conclusion
When administered orally in the engineered microcapsules, the three gut bacteria strains improved survival, recovered kidney function, and reduced buildup of nitrogen-containing waste products in animal models of acute kidney injury and chronic kidney failure. As this biotechnology develops further and is adapted to humans, it could improve quality of life and outcomes for dialysis patients.

Healthy kidneys filter the blood and rid the body of nitrogenous waste products such as urea, creatinine, and ammonia from normal metabolic activities. Patients with acute kidney injury or end stage kidney disease typically require dialysis to perform this function.  Now researchers have identified three strains of mouse gut bacteria that work together to degrade urea and creatinine and recycle them into amino acids without a toxic buildup of ammonia. They housed the microbes in engineered microcapsules that kept them close to one another and limited access to the target nitrogenous waste products.

The results, published in Nature Biomedical Engineering, demonstrate that when administered orally in engineered microcapsules, the isolated microbial strains improved survival, recovered kidney function, and reduced nitrogenous waste products in animal models of acute kidney injury or chronic kidney failure. As this biotechnology develops further and is adapted to human patients, it could improve quality of life and outcomes for dialysis patients.

Previous research into the treatment of kidney injury and disease explored biotechnology solutions and antioxidant drugs, but the biotechnology approaches are invasive, and the drugs have yielded ambiguous results. Development of a safe, effective, non-invasive treatment to reduce the need for dialysis would alleviate significant health burdens for patients. The influence of the gut microbiota on host health is well documented, and the ease of manipulating gut microbial populations with oral supplementation presents therapeutic options. 

Nitrogenous Wastes

Di-Wei Zheng, Pei Pan, et. al. analyzed the in vitro metabolic activity of microbiota from fecal samples derived from four types of mice. They isolated two strains that demonstrated a high capacity to convert either urea or creatinine, nitrogenous waste products, into ammonia. Since ammonia is highly toxic, a third bacterial strain which effectively converted ammonia into amino acids was combined with the other two to form an artificial microbial community.

Bacterial Microbial Ecosystem

To explore the in vivo metabolic activity of the three microbial strains, the researchers engineered a bacterial micro-ecosystem (“BME”) to encapsulate the microbes in microspheres with a semi-permeable nanofilm on the surface. The microspheres assured proximity of the microbial strains to one another within the artificial ecosystem enabling the bacteria to function cohesively rather than allowing them to freely colonize different regions of the host gastrointestinal tract. The nanofilm coating permitted entry to the BME by smaller nitrogenous waste molecules targeted for degradation while preventing access to – and thereby protecting from breakdown – larger proteins.

After first testing the safety profile, the researchers administered the BME to mice and miniature pigs previously subjected to induced acute kidney injury or chronic kidney failure. The animals treated with the BME exhibited higher survival rates and superior blood urea and creatinine clearance compared to animals treated with either peritoneal dialysis or free unencapsulated bacterial strains.  Diagnostic imaging further showed a quick recovery of kidney function in the BME treatment group while the control and dialysis groups exhibited impaired kidney function following the chemical insults. The dialysis group recovered some kidney function over time but exhibited inflammatory changes to the peritoneal membrane.

This research demonstrated that oral administration of three gut bacterial strains contained in engineered microcapsules reduced the workload on damaged kidneys and prolonged survival in the study animals with no adverse effects. A human analog could potentially reduce the need for dialysis.