Population-specific differences in the human microbiome: Factors defining the diversity

Differences in microbial communities at different body habitats define the microbiome composition of the human body. The gut, oral, skin vaginal fluid and tissue microbiome, are pivotal for human development and immune response and cross talk between these microbiomes is evident. Population studies reveal that various factors, such as host genetics, diet, lifestyle, aging, and geographical location are strongly associated with population-specific microbiome differences. The present review discusses the factors that shape microbiome diversity in humans, and microbiome differences in African, Asian and Caucasian populations. Gut microbiome studies show that microbial species Bacteroides is commonly found in individuals living in Western countries (Caucasian populations), while Prevotella is prevalent in non-Western countries (African and Asian populations). This association is mainly due to the high carbohydrate, high fat diet in western countries in contrast to high fibre, low fat diets in African/ Asian regions. Majority of the microbiome studies focus on the bacteriome component; however, interesting findings reveal that increased bacteriophage richness, which makes up the virome component, correlates with decreased bacterial diversity, and causes microbiome dysbiosis. An increase of Caudovirales (bacteriophages) is associated with a decrease in enteric bacteria in inflammatory bowel diseases. Future microbiome studies should evaluate the interrelation between bacteriome and virome to fully understand their significance in the pathogenesis and progression of human diseases. With ethnic health disparities becoming increasingly apparent, studies need to emphasize on the association of population-specific microbiome differences and human diseases, to develop microbiome-based therapeutics. Additionally, targeted phage therapy is emerging as an attractive alternative to antibiotics for bacterial infections. With rapid rise in microbiome research, focus should be on standardizing protocols, advanced bioinformatics tools, and reducing sequencing platform related biases. Ultimately, integration of multi-omics data (genomics, transcriptomics, proteomics and metabolomics) will lead to precision models for personalized microbiome therapeutics advancement.

Unveiling the distinctive variations in multi-omics triggered by TP53 mutation in lung cancer subtypes: An insight from interaction among intratumoral microbiota, tumor microenvironment, and pathology

The TP53 mutation is one of the most common gene mutations in non-small cell lung cancer (NSCLC) and plays a significant role in the occurrence, development, and prognosis of both lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). Recent studies have also suggested the predictive value of TP53 mutations in the response to immunotherapy for NSCLC. It is known that intratumoral microbiota, tumor immune microenvironment (TIME) and histology are associated with the roles of TP53 mutation in NSCLC. However, the intrinsic associations among these three factors and their underlying interaction with TP53 mutation are not well understood. Additionally, the potential of predicting TP53 mutations using deep learning methods has not yet been fully evaluated. In this paper, we comprehensively evaluated the tissue microbiome, host gene expression characteristics, and histopathological slides of 992 NSCLC patients obtained from the cancer genome atlas (TCGA) and validated the findings using multi-omics data of 332 NSCLC patients from the Clinical Proteomic Tumor Analysis Consortium (CPTAC). Compared to LUSC, LUAD exhibited more substantial differences between patients with and without TP53 mutation in all three aspects. In LUAD, our results imply underlying links between the tissue microbiome and immune cell components in the TIME, and show that the abundance of immune cells is reflected in histology slides. Furthermore, we propose a novel multimodal deep learning model that focuses on histopathology images, which achieves an area under the curve (AUC) of 0.84 in LUAD. In summary, TP53 mutation of LUAD resulted more significant changes in intratumoral microbiota, TIME and histology than that of LUSC. And histopathology images can be used to predict TP53 mutation in LUAD with reasonable accuracy.

Evaluation of intestinal biopsy tissue preservation methods to facilitate large-scale mucosal microbiota research

BACKGROUND

Large-scale multicentre studies are needed to understand complex relationships between the gut microbiota, health and disease. Interrogating the mucosal microbiota may identify important biology not captured by stool analysis. Gold standard tissue cryopreservation ('flash freezing') limits large-scale study feasibility. We aimed to compare gut microbiota in gold standard and pragmatic mucosal biopsy storage conditions.

METHODS

We collected endoscopic recto-sigmoid biopsies from 20 adults with inflammatory bowel disease. Biopsies were preserved using three methods: (i) flash freezing (most proximal and distal biopsy sites); (ii) nucleic acid preservative reagents (QIAGEN Allprotect®, Invitrogen RNAlater™, and Zymo DNA/RNA Shield™); and (iii) formalin fixation with paraffin embedding (FFPE), which is used to preserve tissue for clinical histopathology within healthcare settings. Microbiota were sequenced on the MiSeq platform (V4 region, 16S rRNA gene).

FINDINGS

Tissue microbiota were consistent between most proximal and distal tissue suggesting any within-patient variation observed reflected storage condition, not biopsy location. There was no significant difference in alpha-diversity or microbial community profiles of reagent-preserved versus gold standard tissue. FFPE community structure was significantly dissimilar to other tissue samples, driven by differential relative abundance of obligate gut anaerobes; Faecalibacterium, Anaerostipes and Lachnospiraceae. Despite these differences, tissue microbiota grouped by participant regardless of preservation and storage conditions.

INTERPRETATION

Preservative reagents offer a convenient alternative to flash freezing tissue in prospective large-scale mucosal microbiota studies. Whilst less comparable, FFPE provides potential for retrospective microbiota studies using historical samples.

FUNDING

Medical Research Council (MR/T032162/1) and The Leona M. and Harry B. Helmsley Charitable Trust (G-2002-04255).

Characterization of liver, adipose, and fecal microbiome in obese patients with MASLD: links with disease severity and metabolic dysfunction parameters

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) encompasses a range of histological findings from the generally benign simple steatosis to steatohepatitis (MASH) which can progress to fibrosis and cirrhosis. Several factors, including the microbiome, may contribute to disease progression.

RESULTS

Here, we demonstrate links between the presence and abundance of specific bacteria in the adipose and liver tissues, inflammatory genes, immune cell responses, and disease severity. Overall, in MASLD patients, we observed a generalized obesity-induced translocation of gut bacteria to hepatic and adipose tissues. We identified microbial patterns unique to more severely diseased tissues. Specifically, Enterococcus, Granulicatella, and Morganellaceae abundance is positively correlated with immune cell counts and inflammatory gene expression levels, and both genera are significantly enriched in MASH patients. Brevibacterium is enriched in adipose tissues of patients with liver fibrosis.

CONCLUSION

Together, these results provide further insight into the microbial factors that may be driving disease severity. Video Abstract.