Wholegrain fermentation affects gut microbiota composition, phenolic acid metabolism and pancreatic beta cell function in a rodent model of type 2 diabetes

Role of gut microbiome in the outcome of lymphoma patients treated with checkpoint inhibitors-The MicroLinf Study

Biomarkers for immune checkpoint inhibitors (ICIs) response and resistance include PD-L1 expression and other environmental factors, among which the gut microbiome (GM) is gaining increasing interest especially in lymphomas. To explore the potential role of GM in this clinical issue, feces of 30 relapsed/refractory lymphoma (Hodgkin and primary mediastinal B-cell lymphoma) patients undergoing ICIs were collected from start to end of treatment (EoT). GM was profiled through Illumina, that is, 16S rRNA sequencing, and subsequently processed through a bioinformatics pipeline. The overall response rate to ICIs was 30.5%, with no association between patients clinical characteristics and response/survival outcomes. Regarding GM, responder patients showed a peculiar significant enrichment of Lachnospira, while non-responder ones showed higher presence of Enterobacteriaceae (at baseline and maintained till EoT). Recognizing patient-related factors that may influence response to ICIs is becoming critical to optimize the treatment pathway of heavily pretreated, young patients with a potentially long-life expectancy. These preliminary results indicate potential early GM signatures of ICIs response in lymphoma, which could pave the way for future research to improve patients prognosis with new adjuvant strategies.

Early and late gut microbiota signatures of stroke in high salt-fed stroke-prone spontaneously hypertensive rats

The high salt-fed stroke-prone spontaneously hypertensive rat (SHRSP) is a suitable tool to study the mechanisms underlying stroke pathogenesis. Salt intake modifies the gut microbiota (GM) in rats and humans and alterations of the GM have previously been associated with increased stroke occurrence. We aimed to characterize the GM profile in SHRSPs fed a high-salt stroke-permissive diet (Japanese diet, JD), compared to the closely related stroke-resistant control (SHRSR), to identify possible changes associated with stroke occurrence. SHRSPs and SHRSRs were fed a regular diet or JD for 4 weeks (short-term, ST) or a maximum of 10 weeks (long-term, LT). Stroke occurred in SHRSPs on JD-LT, preceded by proteinuria and diarrhoea. The GM of JD-fed SHRSPs underwent early and late compositional changes compared to SHRSRs. An overrepresentation of Streptococcaceae and an underrepresentation of Lachnospiraceae were observed in SHRSPs JD-ST, while in SHRSPs JD-LT short-chain fatty acid producers, e.g. Lachnobacterium and Faecalibacterium, decreased and pathobionts such as Coriobacteriaceae and Desulfovibrio increased. Occludin gene expression behaved differently in SHRSPs and SHRSRs. Calprotectin levels were unchanged. In conclusion, the altered GM in JD-fed SHRSPs may be detrimental to gut homeostasis and contribute to stroke occurrence.

Impact of Combined Prebiotic Galacto-Oligosaccharides and Bifidobacterium breve-Derived Postbiotic on Gut Microbiota and HbA1c in Prediabetic Adults: A Double-Blind, Randomized, Placebo-Controlled Study

The complex interactions between intestinal microbiota and metabolic disorders are well-documented, with implications for glucose metabolism, energy expenditure, and intestinal permeability. Prebiotics induce beneficial changes in gut microbiota composition in prediabetes, while postbiotics can enhance gut barrier function, complementing each other to improve glucose metabolism and insulin sensitivity. This study investigated the effects of a 12-week dietary fibre (DF) supplement on gut health, metabolic function, and diet. The supplement contained konjac glucomannan (KGM), galacto-oligosaccharides (GOSs), and exopolysaccharides (EPSs) from Bifidobacterium breve. In a randomised, double-blind, placebo-controlled, parallel-group clinical trial, 53 prediabetic volunteers were randomly assigned to either a daily DF supplement (YMETA) or a placebo (cellulose microcrystalline) for 12 weeks, followed by a 4-week follow-up. Measurements included gut microbiota composition, glycated haemoglobin (HbA1c), fasting plasma glucose (FPG), plasma lipids, anthropometry, body composition, blood pressure, and dietary intake. The intervention group showed a significant increase in alpha diversity and butyrate-producing bacteria, with reductions in HbA1c and FPG levels below prediabetes thresholds. No significant changes were observed in the placebo group. This study suggests that manipulating the human gut microbiome through dietary interventions could be a promising therapeutic approach to managing prediabetes and preventing or delaying diabetes.

Bridging the gap: exploring the causal relationship between metformin and tumors

Objective

Numerous studies have reported that metformin can reduce the risk of tumor development. However, some of the results of these studies are conflicting, necessitating a more reliable evaluation.

Methods

We conducted a Mendelian randomization phenome-wide association study (MR-PheWAS) of tumors to explore the causal relationship between metformin and tumors. Two cohorts of patients taking metformin were obtained from the UK Biobank. Complete phenotype data of the tumors were obtained from FinnGen_R10. We elucidated the causal relationship using a two-sample Mendelian randomization (MR) analysis. More importantly, we conducted a meta-analysis to ensure relatively unbiased results. In the MR analysis, we used the inverse-variance weighted (IVW) method as the main outcome indicator. Subsequently, two cohorts were integrated for the meta-analysis. Finally, we investigated the mechanisms through mediational MR analysis.

Results

MR analysis revealed that metformin might have a causal relationship with 13 tumor-associated phenotypes in the training cohort. Four phenotypes were validated in the testing cohort. In the training and testing cohorts, metformin exhibited a protective effect against brain meningiomas and malignant neoplasms of the breast (HER-positive), oral cavity, tonsils, and the base of the tongue. Intriguingly, after integrating the results of the two cohorts for the meta-analysis, 12 results were statistically significant. Mediational MR analysis suggested that the effects of metformin on brain meningiomas may be weakened by the presence of the family Oxalobacteraceae.

Conclusion

Metformin exhibits potential preventive and therapeutic effects on four types of tumors: brain meningioma, malignant neoplasms of the breast (HER-positive), oral cavity and tonsils, and the base of the tongue. Large randomized controlled trials are required to confirm these findings.

Exploring the gut microbiota and its potential as a biomarker in gliomas

Gut microbiome alterations are associated with various cancers including brain tumours such as glioma and glioblastoma. The gut communicates with the brain via a bidirectional pathway known as the gut-brain axis (GBA) which is essential for maintaining homeostasis. The gut microbiota produces many metabolites including short chain fatty acids (SCFAs) and essential amino acids such as glutamate, glutamine, arginine and tryptophan. Through the modulation of these metabolites the gut microbiome is able to regulate several functions of brain cells, immune cells and tumour cells including DNA methylation, mitochondrial function, the aryl hydrocarbon receptor (AhR), T-cell proliferation, autophagy and even apoptosis. Here, we summarise current findings on gut microbiome with respect to brain cancers, an area of research that is widely overlooked. Several studies investigated the relationship between gut microbiota and brain tumours. However, it remains unclear whether the gut microbiome variation is a cause or product of cancer. Subsequently, a biomarker panel was constructed for use as a predictive, prognostic and diagnostic tool with respect to multiple cancers including glioma and glioblastoma multiforme (GBM). This review further presents the intratumoural microbiome, a fascinating microenvironment within the tumour as a possible treatment target that can be manipulated to maximise effectiveness of treatment via personalised therapy. Studies utilising the microbiome as a biomarker and therapeutic strategy are necessary to accurately assess the effectiveness of the gut microbiome as a clinical tool with respect to brain cancers.

Association between gut microbiota and onset of type 2 diabetes mellitus: a two-sample Mendelian randomization study

Aim

Mendelian randomization (MR) analysis has been used in the exploration of the role of gut microbiota (GM) in type 2 diabetes mellitus (T2DM); however, it was limited to the genus level. This study herein aims to investigate the relationship of GM, especially at the species level, with T2DM in order to provide some evidence for further exploration of more specific GM taxa and pathway abundance in T2DM.

Methods

This two-sample MR study was based on the summary statistics of GM from the available genome-wide association study (GWAS) meta-analysis conducted by the MiBioGen consortium as well as the Dutch Microbiome Project (DMP), whereas the summary statistics of T2DM were obtained from the FinnGen consortium released data. Inverse variance weighted (IVW), MR-Egger, strength test (F), and weighted median methods were used to examine the causal association between GM and the onset of T2DM. Cochran's Q statistics was employed to quantify the heterogeneity of instrumental variables. Bonferroni's correction was conducted to correct the bias of multiple testing. We also performed reverse causality analysis.

Results

The corrected IVW estimates suggested the increased relative abundance of family Oxalobacteraceae (OR = 1.0704) and genus Oxalobacter (OR = 1.0874), respectively, were associated with higher odds of T2DM, while that of species faecis (OR = 0.9460) had a negative relationship with T2DM. The relationships of class Betaproteobacteria, family Lactobacillaceae, species finegoldii, and species longum with T2DM were also significant according to the IVW results (all P < 0.05).

Conclusions

GM had a potential causal association with T2DM, especially species faecis, finegoldii, and longum. Further studies are still needed to clarify certain results that are contradictory with previous findings.

Comparison of the relative impacts of acute consumption of an inulin-enriched diet, milk kefir or a commercial probiotic product on the human gut microbiome and metabolome

It has been established that the human gut microbiota is central to health, and, consequently, there has been a growing desire to positively modulate its composition and/or function through, for example, the use of fermented foods, prebiotics or probiotics. Here, we compare the relative impact of the daily consumption of an inulin-enriched diet (n = 10), a commercial probiotic-containing fermented milk product (FMP) (n = 10), or a traditional kefir FMP (n = 9), over a 28-day period on the gut microbiome and urine metabolome of healthy human adults. None of the treatments resulted in significant changes to clinical parameters or biomarkers tested. However, shotgun metagenomic analysis revealed that kefir consumption resulted in a significant change in taxonomy, in the form of an increased abundance of the sub-dominant FMP-associated species Lactococcus raffinolactis, which further corresponded to shifts in the urine metabolome. Overall, our results indicated that daily consumption of a single portion of kefir alone resulted in detectable changes to the gut microbiota and metabolome of consumers.

Microbial gene expression during hibernation in arctic ground squirrels: greater differences across gut sections than in response to pre-hibernation dietary protein content

Obligate seasonal hibernators fast for 5-9 months depending on species yet resist muscle atrophy and emerge with little lean mass loss. The role of the gut microbiome in host nitrogen metabolism during hibernation is therefore of considerable interest, and recent studies support a role for urea nitrogen salvage (UNS) in host-protein conservation. We were interested in the effect of pre-hibernation diet on UNS and the microbial provision of essential amino acids (EAAs) during hibernation; therefore, we conducted a study whereby we fed arctic ground squirrels (Urocitellus parryii) pre-hibernation diets containing 9% vs. 18% protein and compared the expression of gut bacterial urease and amino acid (AA) metabolism genes in 4 gut sections (cecum mucosa, cecum lumen, small intestine [SI] mucosa, and SI lumen) during hibernation. We found that pre-hibernation dietary protein content did not affect expression of complete bacterial AA pathway genes during hibernation; however, several individual genes within EAA pathways were differentially expressed in squirrels fed 18% pre-hibernation dietary protein. Expression of genes associated with AA pathways was highest in the SI and lowest in the cecum mucosa. Additionally, the SI was the dominant expression site of AA and urease genes and was distinct from other sections in its overall microbial functional and taxonomic composition. Urease expression in the gut microbiome of hibernating squirrels significantly differed by gut section, but not by pre-hibernation dietary protein content. We identified two individual genes that are part of the urea cycle and involved in arginine biosynthesis, which were significantly more highly expressed in the cecum lumen and SI mucosa of squirrels fed a pre-hibernation diet containing 18% protein. Six bacterial genera were responsible for 99% of urease gene expression: Cupriavidus, Burkholderia, Laribacter, Bradhyrizobium, Helicobacter, and Yersinia. Although we did not find a strong effect of pre-hibernation dietary protein content on urease or AA metabolism gene expression during hibernation, our data do suggest the potential for pre-hibernation diet to modulate gut microbiota function during hibernation, and further investigations are warranted.

Biochemical Changes Induced by the Administration of Cannabis sativa Seeds in Diabetic Wistar Rats

The present pilot study investigates the blood biochemical changes induced by hemp seeds in rats with diabetes. The composition of industrial hemp seeds, antioxidant activity, identification and quantification of phenols and fatty acids from hemp oil were determined. The Wistar adult rats used in the experiment were divided into three groups (n = 6) and kept under standard conditions. Group one, the control group (individuals without diabetes), and group two (diabetic individuals) received water and normal food ad libitum, while the third group, also including diabetic individuals, received specific food (hemp seeds) and water ad libitum. Subsequent blood biochemical parameters were determined. Hemp seeds had higher phenol (14 compounds), flavonoids and PUFA contents compared to other plants seeds. In addition, the antioxidant activity in Cannabis sativa was also increased. Moreover, the ratio between n-6 and n-3 was 4.41, ideal for different diseases. Additionally, all biochemical parameters showed significant changes following the treatment. It was shown that high doses of hemp seeds decreased diabetes-induced biochemical damage in rats most probably due to the high content of active compounds. In order to use these seeds in humans, it is essential to find out which hemp compounds are particularly responsible for these effects. Moreover, for the objective investigation of their effects, longer-term studies are needed.