Sex-specific associations between AD genotype and the microbiome of human amyloid beta knock-in (hAß-KI) mice.

INTRODUCTION: Emerging evidence links changes in the gut microbiome to late-onset Alzheimer's disease (LOAD), necessitating examination of AD mouse models with consideration of the microbiome. METHODS: We used shotgun metagenomics and untargeted metabolomics to study the human amyloid beta knock-in (hAß-KI) murine model for LOAD compared to both wild-type (WT) mice and a model for early-onset AD (3xTg-AD). RESULTS: Eighteen-month female (but not male) hAß-KI microbiomes were distinct from WT microbiomes, with AD genotype accounting for 18% of the variance by permutational multivariate analysis of variance (PERMANOVA). Metabolomic diversity differences were observed in females, however no individual metabolites were differentially abundant. hAß-KI mice microbiomes were distinguishable from 3xTg-AD animals (81% accuracy by random forest modeling), with separation primarily driven by Romboutsia ilealis and Turicibacter species. Microbiomes were highly cage specific, with cage assignment accounting for more than 40% of the PERMANOVA variance between the groups. DISCUSSION: These findings highlight a sex-dependent variation in the microbiomes of hAß-KI mice and underscore the importance of considering the microbiome when designing studies that use murine models for AD. HIGHLIGHTS: Microbial diversity and the abundance of several species differed in human amyloid beta knock-in (hAß-KI) females but not males. Correlations to Alzheimer's disease (AD) genotype were stronger for the microbiome than the metabolome. Microbiomes from hAß-KI mice were distinct from 3xTg-AD mice. Cage effects accounted for most of the variance in the microbiome and metabolome.

The NUTRIENT Trial (NUTRitional Intervention among myEloproliferative Neoplasms): Results from a Randomized Phase I Pilot Study for Feasibility and Adherence.

PURPOSE: Chronic inflammation is integral to myeloproliferative neoplasm (MPN) pathogenesis. JAK inhibitors reduce cytokine levels, but not without significant side effects. Nutrition is a low-risk approach to reduce inflammation and ameliorate symptoms in MPN. We performed a randomized, parallel-arm study to determine the feasibility of an education-focused Mediterranean diet intervention among patients with MPN. EXPERIMENTAL DESIGN: We randomly assigned patients with MPN to either a Mediterranean diet or standard U.S. Dietary Guidelines for Americans (USDA). Groups received equal but separate education with registered dietician counseling and written dietary resources. Patients were prospectively followed for feasibility, adherence, and symptom burden assessments. Biological samples were collected at four timepoints during the 15-week study to explore changes in inflammatory biomarkers and gut microbiome. RESULTS: The Mediterranean diet was as easy to follow for patients with MPN as the standard USDA diet. Approximately 80% of the patients in the Mediterranean diet group achieved a Mediterranean Diet Adherence Score of ≥8 throughout the entire active intervention period, whereas less than 50% of the USDA group achieved a score of ≥8 at any timepoint. Improvement in symptom burden was observed in both diet groups. No significant changes were observed in inflammatory cytokines. The diversity and composition of the gut microbiome remained stable throughout the duration of the intervention. CONCLUSIONS: With dietician counseling and written education, patients with MPN can adhere to a Mediterranean eating pattern. Diet interventions may be further developed as a component of MPN care, and potentially incorporated into the management of other hematologic conditions. SIGNIFICANCE: Diet is a central tenant of management of chronic conditions characterized by subclinical inflammation, such as cardiovascular disease, but has not entered the treatment algorithm for clonal hematologic disorders. Here, we establish that a Mediterranean diet intervention is feasible in the MPN patient population and can improve symptom burden. These findings warrant large dietary interventions in patients with hematologic disorders to test the impact of diet on clinical outcomes.

Characterizing the microbiome of patients with myeloproliferative neoplasms during a Mediterranean diet intervention.

Myeloproliferative neoplasms (MPNs) are a class of rare hematological malignancies that result in the overproduction of myeloid lineage cells. These malignancies result in increased cytokine production and inflammation, which correlate with worsened symptom burden and prognosis. Other than bone marrow transplantation, there is no cure for myeloproliferative neoplasms. As such, treatments focus on reducing thrombotic risk, inflammation, and symptom burden. Because current pharmacological treatments carry significant side effects, there is a need to explore low-risk therapies that may modulate inflammation and alleviate symptom burden. One potential way to achieve this is adherence to a Mediterranean (MED) diet, which is rich in anti-inflammatory foods, reduces inflammatory biomarkers, and beneficially alters the gut microbiome. We performed a 15-week clinical trial of 28 individuals with MPN who were randomized to dietary counseling based on either a Mediterranean diet or standard U.S. Guidelines for Americans. Our primary objective was to determine whether MPN patients could adopt a Mediterranean eating pattern when supported with dietician counseling. As exploratory endpoints, we investigated the impact of diet and inflammation on the gut microbiome. Using shotgun metagenomic sequencing, we found that microbiome diversity and composition were stable throughout the study duration in both cohorts. Furthermore, we discovered significant differences in the microbiomes between MPN subtypes, such as increased beta-dispersion in subjects with myelofibrosis. Lastly, we found several significant correlations between the abundance of multiple bacterial taxa and cytokine levels. Together, this study provides insight into the interaction between diet, inflammation, and the gut microbiome. IMPORTANCE The gut microbiome serves as an interface between the host and the diet. Diet and the gut microbiome both play important roles in managing inflammation, which is a key aspect of myeloproliferative neoplasm (MPN). Studies have shown that a Mediterranean (MED) diet can reduce inflammation. Therefore, we longitudinally characterized the gut microbiomes of MPN patients in response to Mediterranean or standard 2020 US Guidelines for Americans dietary counseling to determine whether there were microbiome-associated changes in inflammation. We did not find significant changes in the gut microbiome associated with diet, but we did find several associations with inflammation. This research paves the way for future studies by identifying potential mechanistic targets implicated in inflammation within the MPN gut microbiome.

The NUTRIENT Trial (NUTRitional Intervention among myEloproliferative Neoplasms): Feasibility Phase.

Purpose: Chronic inflammation is integral to Myeloproliferative Neoplasm (MPN) pathogenesis. JAK inhibitors reduce cytokine levels, but not without significant side effects. Nutrition is a low-risk approach to reduce inflammation and ameliorate symptoms in MPN. We performed a randomized, parallel-arm study to determine the feasibility of an education-focused Mediterranean diet intervention among MPN patients. Experimental Design: We randomly assigned participants to either a Mediterranean diet or standard US Dietary Guidelines for Americans (USDA). Groups received equal but separate education with registered dietician counseling and written dietary resources. Patients were prospectively followed for feasibility, adherence, and symptom burden assessments. Biological samples were collected at four time points during the 15-week study to explore changes in inflammatory biomarkers and gut microbiome. Results: The Mediterranean diet was as easy to follow for MPN patients as the standard USDA diet. Over 80% of the patients in the Mediterranean diet group achieved a Mediterranean Diet Adherence Score of ≥8 throughout the entire active intervention period, whereas less than 50% of the USDA group achieved a score of ≥8 at any time point. Improvement in symptom burden was observed in both diet groups. No significant changes were observed in inflammatory cytokines. The diversity and composition of the gut microbiome remained stable throughout the duration of the intervention. Conclusions: With dietician counseling and written education MPN patients can adhere to a Mediterranean eating pattern. Diet interventions may be further developed as a component of MPN care, and potentially even be incorporated into the management of other chronic clonal hematologic conditions.

Fecal Putative Uropathogen Abundance and Antibiotic Resistance Gene Carriage in Women With Refractory Recurrent Urinary Tract Infection Treated With Fecal Microbiota Transplantation.

OBJECTIVE: The aims of this study were to describe the fecal relative abundance of potentially uropathogenic bacteria and to analyze antibiotic resistance genes before and after fecal microbiota transplantation in women with recurrent urinary tract infection (UTI). METHODS: Shotgun sequencing was performed on fecal samples from 3 donors and 4 women with recurrent UTI who underwent transplantation. Recipient samples were sequenced at baseline and at 4 time points through 6 months postintervention. Relative fecal uropathogen abundance was analyzed by species and participant using descriptive statistics. Antibiotic resistance gene abundance was assigned, normalized, and compared between donors and recipients at baseline and postintervention using an abundance bar plot, nonmetric multidimensional scaling, and pairwise permutational multivariate analysis of variance. RESULTS: The median (range) relative abundance of Escherichia coli in all fecal samples from women with recurrent UTI was 0% (0%-5.10%); Enterococcus faecalis, 0% (0%-0.20%); Enterococcus faecium, 0% (0%-1.90%); Klebsiella pneumoniae, 0% (0%-0.10%); and Pseudomonas aeruginosa, 0% (0%-0.10%). Gut microbes carried genes conferring resistance to antibiotics used for UTI. No significant difference was seen in antibiotic resistance gene carriage after transplantation compared with baseline (P=0.22, R2=0.08 at 3 months). Antibiotic gene composition and abundance were significantly associated with the individual from whom the sample came (P=0.004, R2=0.78 at 3 months). CONCLUSIONS: Exploratory analysis of gut microbiomes in women with recurrent UTI identifies no or low relative putative uropathogen abundance for all species examined. Antibiotic resistance gene carriage persisted after fecal microbiota transplantation, although conclusions are limited by small sample size.

Distinct colon mucosa microbiomes associated with tubular adenomas and serrated polyps.

Colorectal cancer is the second most deadly and third most common cancer in the world. Its development is heterogenous, with multiple mechanisms of carcinogenesis. Two distinct mechanisms include the adenoma-carcinoma sequence and the serrated pathway. The gut microbiome has been identified as a key player in the adenoma-carcinoma sequence, but its role in serrated carcinogenesis is less clear. In this study, we characterized the gut microbiome of 140 polyp-free and polyp-bearing individuals using colon mucosa and fecal samples to determine if microbiome composition was associated with each of the two key pathways. We discovered significant differences between the microbiomes of colon mucosa and fecal samples, with sample type explaining 10-15% of the variation observed in the microbiome. Multiple mucosal brushings were collected from each individual to investigate whether the gut microbiome differed between polyp and healthy intestinal tissue, but no differences were found. Mucosal aspirate sampling revealed that the microbiomes of individuals with tubular adenomas and serrated polyps were significantly different from each other and polyp-free individuals, explaining 1-4% of the variance in the microbiome. Microbiome composition also enabled the accurate prediction of subject polyp types using Random Forest, which produced an area under curve values of 0.87-0.99. By directly sampling the colon mucosa and distinguishing between the different developmental pathways of colorectal cancer, our study helps characterize potential mechanistic targets for serrated carcinogenesis. This research also provides insight into multiple microbiome sampling strategies by assessing each method's practicality and effect on microbial community composition.

Fecal Microbial Community Composition in Myeloproliferative Neoplasm Patients Is Associated with an Inflammatory State.

The capacity of the human microbiome to modulate inflammation in the context of cancer is becoming increasingly clear. Myeloproliferative neoplasms (MPNs) are chronic hematologic malignancies in which inflammation plays a key role in disease initiation, progression, and symptomatology. To better understand the composition of the gut microbiome in patients with MPN, triplicate fecal samples were collected from 25 MPN patients and 25 non-MPN controls. Although most of the variance between the microbial community compositions could be attributed to the individual (permutational analysis of variance [PERMANOVA], R2 = 0.92, P = 0.001), 1.7% of the variance could be attributed to disease status (MPN versus non-MPN). When a more detailed analysis was performed, significantly fewer reads mapping to a species of Phascolarctobacterium, a microbe previously associated with reduced inflammation, were found in MPNs. Further, our data revealed an association between Parabacteroides and tumor necrosis factor alpha (TNF-α), an inflammatory cytokine elevated in MPNs. Taken together, our results indicate a significant difference in the microbiome of MPN patients compared to non-MPN controls, and we identify specific species which may have a role in the chronic inflammation central to this disease. IMPORTANCE MPNs are chronic blood cancers in which inflammation plays a key role in disease initiation, progression, and symptomatology. The gut microbiome modulates normal blood development and inflammation and may also impact the development and manifestation of blood cancers. Therefore, the microbiome may be an important modulator of inflammation in MPN and could potentially be leveraged therapeutically in this disease. However, the relationship between the gut microbiome and MPNs has not been defined. Therefore, we performed an evaluation of the MPN microbiome, comparing the microbiomes of MPN patients with healthy donors and between MPN patients with various states of disease.

Longitudinal Analysis of the Microbiome and Metabolome in the 5xfAD Mouse Model of Alzheimer's Disease.

Recent reports implicate gut microbiome dysbiosis in the onset and progression of Alzheimer's disease (AD), yet studies involving model animals overwhelmingly omit the microbial perspective. Here, we evaluate longitudinal microbiomes and metabolomes from a popular transgenic mouse model for familial AD (5xfAD). Cecal and fecal samples from 5xfAD and wild-type B6J (WT) mice from 4 to 18 months of age were subjected to shotgun Illumina sequencing. Metabolomics was performed on plasma and feces from a subset of the same animals. Significant genotype, sex, age, and cage-specific differences were observed in the microbiome, with the variance explained by genotype at 4 and 18 months of age rising from 0.9 to 9% and 0.3 to 8% for the cecal and fecal samples, respectively. Bacteria at significantly higher abundances in AD mice include multiple Alistipes spp., two Ligilactobacillus spp., and Lactobacillus sp. P38, while multiple species of Turicibacter, Lactobacillus johnsonii, and Romboutsia ilealis were less abundant. Turicibacter is similarly depleted in people with AD, and members of this genus both consume and induce the production of gut-derived serotonin. Contradicting previous findings in humans, serotonin is significantly more concentrated in the blood of older 5xfAD animals compared to their WT littermates. 5xfAD animals exhibited significantly lower plasma concentrations of carnosine and the lysophospholipid lysoPC a C18:1. Correlations between the microbiome and metabolome were also explored. Taken together, these findings strengthen the link between Turicibacter abundance and AD, provide a basis for further microbiome studies of murine models for AD, and suggest that greater control over animal model microbiomes is needed in AD research. IMPORTANCE Microorganisms residing within the gastrointestinal tract are implicated in the onset and progression of Alzheimer's disease (AD) through the mediation of inflammation, exchange of small-molecules across the blood-brain barrier, and stimulation of the vagus nerve. Unfortunately, most animal models for AD are housed under conditions that do not reflect real-world human microbial exposure and do not sufficiently account for (or meaningfully consider) variations in the microbiome. An improved understanding of AD model animal microbiomes will increase model efficacy and the translatability of research findings into humans. Here, we present the characterization of the microbiome and metabolome of the 5xfAD mouse model, which is one of the most common animal models for familial AD. The manuscript highlights the importance of considering the microbiome in study design and aims to lay the groundwork for future studies involving mouse models for AD.

Microbiome distinctions between the CRC carcinogenic pathways.

Colorectal cancer (CRC) is the third most commonly diagnosed cancer, the third leading cause of cancer-related deaths, and has been on the rise among young adults in the United States. Research has established that the colonic microbiome is different in patients with CRC compared to healthy controls, but few studies have investigated if and how the microbiome may relate to CRC progression through the serrated pathway versus the adenoma-carcinoma sequence.Our view is that progress in CRC microbiome research requires consideration of how the microbiome may contribute to CRC carcinogenesis through the distinct pathways that lead to CRC, which could enable the creation of novel and tailored prevention, screening, and therapeutic interventions. We first highlight the limitations in existing CRC microbiome research and offer corresponding solutions for investigating the microbiome's role in the adenoma-carcinoma sequence and serrated pathway. We then summarize the findings in the select human studies that included data points related to the two major carcinogenic pathways. These studies investigate the microbiome in CRC carcinogenesis and 1) utilize mucosal samples and 2) compare polyps or tumors by histopathologic type, molecular/genetic type, or location in the colon.Key findings from these studies include: 1) Fusobacterium is associated with right-sided, more advanced, and serrated lesions; 2) the colons of people with CRC have bacteria typically associated with normal oral flora; and 3) colons from people with CRC have more biofilms, and these biofilms are predominantly located in the proximal colon (single study).