The effect of host genetics on the gut microbiome

Advancing genetic improvement in the omics era: status and priorities for United States aquaculture

BACKGROUND

The innovations of the "Omics Era" have ushered in significant advancements in genetic improvement of agriculturally important animal species through transforming genetics, genomics and breeding strategies. These advancements were often coordinated, in part, by support provided over 30 years through the 1993-2023 National Research Support Project 8 (NRSP8, National Animal Genome Research Program, NAGRP) and affiliate projects focused on enabling genomic discoveries in livestock, poultry, and aquaculture species. These significant and parallel advances demand strategic planning of future research priorities. This paper, as an output from the May 2023 Aquaculture Genomics, Genetics, and Breeding Workshop, provides an updated status of genomic resources for United States aquaculture species, highlighting major achievements and emerging priorities.

MAIN TEXT

Finfish and shellfish genome and omics resources enhance our understanding of genetic architecture and heritability of performance and production traits. The 2023 Workshop identified present aims for aquaculture genomics/omics research to build on this progress: (1) advancing reference genome assembly quality; (2) integrating multi-omics data to enhance analysis of production and performance traits; (3) developing resources for the collection and integration of phenomics data; (4) creating pathways for applying and integrating genomics information across animal industries; and (5) providing training, extension, and outreach to support the application of genome to phenome. Research focuses should emphasize phenomics data collection, artificial intelligence, identifying causative relationships between genotypes and phenotypes, establishing pathways to apply genomic information and tools across aquaculture industries, and an expansion of training programs for the next-generation workforce to facilitate integration of genomic sciences into aquaculture operations to enhance productivity, competitiveness, and sustainability.

CONCLUSION

This collective vision of applying genomics to aquaculture breeding with focus on the highlighted priorities is intended to facilitate the continued advancement of the United States aquaculture genomics, genetics and breeding research community and industries. Critical challenges ahead include the practical application of genomic tools and analytical frameworks beyond academic and research communities that require collaborative partnerships between academia, government, and industry. The scope of this review encompasses the use of omics tools and applications in the study of aquatic animals cultivated for human consumption in aquaculture settings throughout their life-cycle.

Effects of Limosilactobacillus fermentum KBL375 on Immune Enhancement and Gut Microbiota Composition in Cyclophosphamide-Induced Immunosuppressed Mice

This study evaluated the immune-enhancing efficacy of Limosilactobacillus fermentum KBL375 isolated from the feces of healthy Koreans. KBL375-treated splenocytes showed enhancement of cytotoxicity against YAC-1 cells, the target of natural killer (NK) cells, with an increase in CD335, granzyme B, perforin, and interferon-gamma (IFN-γ). Oral administration of KBL375 in mice with cyclophosphamide (CP)-induced immunosuppression improved body weight and immune functions, including immune organ indices, lymphocyte proliferations, and immunoglobulin (Ig) A levels. Notably, KBL375 increased NK cell cytotoxicity and proportion in immunosuppressed mice. Perforin/IFN-γ expression levels, which indicated NK cell activation, were also increased in KBL375-treated mice. Furthermore, KBL375 led to an increase in beneficial microbes, such as Bifidobacterium, in the gut microbiome of immunosuppressed mice, fostering a favorable intestinal microbial environment. These comprehensive results suggest that KBL375 exhibits potent immune regulatory functions and positively influences the gut microbiota, implying its potential as a probiotic agent for immune enhancement.

Utilizing a novel fecal sampling method to examine resistance of the honey bee (Apis mellifera) gut microbiome to a low dose of tetracycline

Disruption of host-associated microbial communities can have detrimental impacts on host health. However, the capacity of individual host-associated microbial communities to resist disturbance has not been well defined. Using a novel fecal sampling method for honey bees (Apis mellifera), we examined the resistance of the honey bee gut microbiome to disruption from a low dose of the antibiotic, tetracycline (4.5 μg). Prior to the experiment, bacterial communities from fecal samples were compared to communities from dissected whole guts of the same individuals to ensure fecal samples accurately represented the gut microbiome. Fecal samples were collected from lab-caged honey bees prior to, and five days after, tetracycline exposure to assess how antibiotic disturbance affected the communities of individuals. We used metrics of alpha and beta diversity calculated from 16S rRNA gene amplicon sequences to compare gut community structure. Low dose tetracycline exposure did not consistently change honey bee gut microbiome structure, but there was individual variation in response to exposure and specific taxa (one ASV assigned to Lactobacillus kunkeei and one ASV in the genus Bombella) were differentially abundant following tetracycline treatment. To assess whether individual variation could be influenced by the presence of tetracycline resistance genes, we quantified the abundance of tet(B) and tet(M) with qPCR. The abundance of tet(M) prior to tetracycline treatment was negatively correlated with change in community membership, assessed by difference in Jaccard dissimilarity over the five-day experiment. Our results suggest that the honey bee gut microbiome has some ability to resist or recover from antibiotic-induced change, specific taxa may vary in their susceptibility to tetracycline exposure, and antibiotic resistance genes may contribute to gut microbiome resistance.

The circadian clock gene period regulates the composition and daily bacterial load of the gut microbiome in Drosophila melanogaster

While Drosophila melanogaster serves as a crucial model for investigating both the circadian clock and gut microbiome, our understanding of their relationship in this organism is still limited. Recent analyses suggested that the Drosophila gut microbiome modulates the host circadian transcriptome to minimize rapid oscillations in response to changing environments. Here, we examined the composition and abundance of the gut microbiota in wild-type and arrhythmic per01 flies, under 12 h:12 h light: dark (12:12 LD) and constant darkness (DD) conditions. The gut microbiota of wild-type and per01 flies showed differences in composition, suggesting that the D. melanogaster circadian gene per has a role in shaping the gut microbiome. In 12:12 LD and DD conditions, per01 mutants showed significant daily variations in gut bacterial quantity, unlike wild-type flies. This suggests that per is involved in maintaining the daily stability of gut microbiome load in D. melanogaster. Expanding these analyses to other fly strains with disrupted circadian clocks will clarify whether these effects originate from a circadian function of per or from its possible pleiotropic effects. Finally, some gut bacteria exhibited significant 24 h fluctuations in their relative abundance, which appeared independent from the fly circadian clock, suggesting that certain gut commensal bacteria in Drosophila may possess a host-independent circadian clock.

Advances in multi-omics integrated analysis methods based on the gut microbiome and their applications

The gut microbiota actually shares the host's physical space and affects the host's physiological functions and health indicators through a complex network of interactions with the host. However, its role as a determinant of host health and disease is often underestimated. With the emergence of new technologies including next-generation sequencing (NGS) and advanced techniques such as microbial community sequencing, people have begun to explore the interaction mechanisms between microorganisms and hosts at various omics levels such as genomics, transcriptomics, metabolomics, and proteomics. With the enrichment of multi-omics integrated analysis methods based on the microbiome, an increasing number of complex statistical analysis methods have also been proposed. In this review, we summarized the multi-omics research analysis methods currently used to study the interaction between the microbiome and the host. We analyzed the advantages and limitations of various methods and briefly introduced their application progress.

Investigation of Intestinal Microbes of Five Zokor Species Based on 16S rRNA Sequences

Zokor is a group of subterranean rodents that are adapted to underground life and feed on plant roots. Here, we investigated the intestinal microbes of five zokor species (Eospalax cansus, Eospalax rothschildi, Eospalax smithi, Myospalax aspalax, and Myospalax psilurus) using 16S amplicon technology combined with bioinformatics. Microbial composition analysis showed similar intestinal microbes but different proportions among five zokor species, and their dominant bacteria corresponded to those of herbivores. To visualize the relationships among samples, PCoA and PERMANOVA tests showed that the intestinal microbes of zokors are largely clustered by host species, but less so by genetics and geographical location. To find microbes that differ among species, LefSe analysis identified Lactobacillus, Muribaculaceae, Lachnospiraceae_NK4A136_group, unclassified_f_Christensenellaceae, and Desulfovibrio as biomarkers for E. cansus, E. rothschildi, E. smithi, M. aspalax, and M. psilurus, respectively. PICRUSt metagenome predictions revealed enriched microbial genes for carbohydrate and amino acid metabolism in E. cansus and E. smithi, and for cofactor and vitamin metabolism as well as glycan biosynthesis and metabolism in E. rothschildi, M. aspalax, and M. psilurus. Our results demonstrated differences in the microbial composition and functions among five zokor species, potentially related to host genetics, and host ecology including dietary habits and habitat environment. These works would provide new insight into understanding how subterranean zokors adapt to their habitats by regulating intestinal microbes.

The host genotype actively shapes its microbiome across generations in laboratory mice

BACKGROUND

The microbiome greatly affects health and wellbeing. Evolutionarily, it is doubtful that a host would rely on chance alone to pass on microbial colonization to its offspring. However, the literature currently offers only limited evidence regarding two alternative hypotheses: active microbial shaping by host genetic factors or transmission of a microbial maternal legacy.

RESULTS

To further dissect the influence of host genetics and maternal inheritance, we collected two-cell stage embryos from two representative wild types, C57BL6/J and BALB/c, and transferred a mixture of both genotype embryos into hybrid recipient mice to be inoculated by an identical microbiome at birth.

CONCLUSIONS

Observing the offspring for six generations unequivocally emphasizes the impact of host genetic factors over maternal legacy in constant environments, akin to murine laboratory experiments. Interestingly, maternal legacy solely controlled the microbiome in the first offspring generation. However, current evidence supporting maternal legacy has not extended beyond this initial generation, resolving the aforementioned debate. Video Abstract.

Characteristics of the gut microbiota and the effect of Bifidobacterium in very early-onset inflammatory bowel disease patients with IL10RA mutations

Very early-onset inflammatory bowel disease (VEO-IBD) is a distinct subtype of inflammatory bowel disease (IBD) characterized by onset before the age of 6 years, and patients often exhibit more severe clinical features. Interleukin 10 receptor alpha (IL10RA) is a hotspot mutation in the Chinese population and is associated with a poor prognosis closely linked to the onset of IBD. However, limited knowledge exists regarding how the IL10RA mutation influences the host microbiota and its role in disease development. We employed 16S rRNA sequencing to conduct a comprehensive assessment of microbial changes in different types of IBD, employed database to thoroughly examine the influence of Bifidobacterium in IBD and to demonstrate a potential positive effect exerted by Bifidobacterium breve M16V (M16V) through a mouse model. The study demonstrated a significant reduction in the abundance and diversity of the gut microbiota among children with IL10RA mutations compared to those with late-onset pediatric IBD and nonmutated VEO-IBD. Furthermore, the analysis identified genera capable of distinguishing between various types of IBD, with the genus Bifidobacterium emerging as a potential standalone diagnostic indicator and Bifidobacterium may also be involved in related pathways that influence the progression of IBD, such as the biosynthesis of amino acids and inflammation-related pathways. This study corroborated the efficacy of Bifidobacterium in alleviating intestinal inflammation. The impact of IL10RA mutations on VEO-IBD may be mediated by alterations in microbes. M16V demonstrates efficacy in alleviating colitis and holds promise as a novel microbial therapy.

Advances in Vibrio-related infection management: an integrated technology approach for aquaculture and human health

Vibrio species pose significant threats worldwide, causing mortalities in aquaculture and infections in humans. Global warming and the emergence of worldwide strains of Vibrio diseases are increasing day by day. Control of Vibrio species requires effective monitoring, diagnosis, and treatment strategies at the global scale. Despite current efforts based on chemical, biological, and mechanical means, Vibrio control management faces limitations due to complicated implementation processes. This review explores the intricacies and challenges of Vibrio-related diseases, including accurate and cost-effective diagnosis and effective control. The global burden due to emerging Vibrio species further complicates management strategies. We propose an innovative integrated technology model that harnesses cutting-edge technologies to address these obstacles. The proposed model incorporates advanced tools, such as biosensing technologies, the Internet of Things (IoT), remote sensing devices, cloud computing, and machine learning. This model offers invaluable insights and supports better decision-making by integrating real-time ecological data and biological phenotype signatures. A major advantage of our approach lies in leveraging cloud-based analytics programs, efficiently extracting meaningful information from vast and complex datasets. Collaborating with data and clinical professionals ensures logical and customized solutions tailored to each unique situation. Aquaculture biotechnology that prioritizes sustainability may have a large impact on human health and the seafood industry. Our review underscores the importance of adopting this model, revolutionizing the prognosis and management of Vibrio-related infections, even under complex circumstances. Furthermore, this model has promising implications for aquaculture and public health, addressing the United Nations Sustainable Development Goals and their development agenda.

Mendelian randomization and bioinformatics unveil potential links between gut microbial genera and colorectal cancer

Background

Colorectal cancer (CRC) poses a significant global health burden, with high incidence and mortality rates. Despite advances in diagnostic and therapeutic modalities, early diagnosis remains critical for improved outcomes. Recent research has realized the important role of gut microbiota in CRC development, highlighting the need to elucidate potential relationships.

Methods

In this study, we employed Mendelian randomization (MR) to establish a robust potential link between gut microbial genera and CRC. Data from the MiBioGen database provided curated genome-wide association study (GWAS) summary datasets for microbial genera, while the Finngen database provided CRC outcome data. Instrumental variables (IVs) were identified based on genetic variants associated with gut microbiota. Various MR methods, including Inverse Variance Weighted (IVW), Weighted Median, Weighted Mode, Simple Mode, and MR-Egger, were employed to estimate potential effects. Functional analysis of genes near single nucleotide polymorphisms (SNPs) was performed to unravel potential pathways.

Results

Analysis of microbial genera identified five potentially associated with CRC: Eubacterium fissicatena group, Anaerofilum, Defluviitaleaceae UCG011, Ruminococcus 2, and Sutterella. Notably, Defluviitaleaceae UCG011 emerged as the only risk factor. Gene analysis revealed hub genes PTPRD and DSCAM near Defluviitaleaceae UCG011 associated SNPs. Expression analysis showed that PTPRD decreased in colon cancer and DSCAM decreased in rectal cancer. The methylation status of the PTPRD gene promoter region indicated potential regulatory alterations.

Conclusion

This study establishes a potential relationship between five specific gut microbial genera, particularly Defluviitaleaceae UCG011, and CRC. Hub genes PTPRD and DSCAM provide insights into potential molecular mechanisms, suggesting the potential role of Defluviitaleaceae UCG011 in modulating the initiation and progression of CRC. Further research is essential to validate these associations and delve deeper into therapeutic implications.

Shared environments complicate the use of strain-resolved metagenomics to infer microbiome transmission

In humans and other social animals, social partners have more similar microbiomes than expected by chance, suggesting that social contact transfers microorganisms. Yet, social microbiome transmission can be difficult to identify based on compositional data alone. To overcome this challenge, recent studies have used information about microbial strain sharing (i.e., the shared presence of highly similar microbial sequences) to infer transmission. However, the degree to which strain sharing is influenced by shared traits and environments among social partners, rather than transmission per se, is not well understood. Here, we first use a fecal microbiota transplant dataset to show that strain sharing can recapitulate true transmission networks under ideal settings when donor-recipient pairs are unambiguous and recipients are sampled shortly after transmission. In contrast, in gut metagenomes from a wild baboon population, we find that demographic and environmental factors can override signals of strain sharing among social partners. We conclude that strain-level analyses provide useful information about microbiome similarity, but other facets of study design, especially longitudinal sampling and careful consideration of host characteristics, are essential for inferring the underlying mechanisms.

Multi-omics analysis reveals the genetic and environmental factors in shaping the gut resistome of a keystone rodent species

Understanding the emergence and spread of antibiotic resistance genes (ARGs) in wildlife is critical for the health of humans and animals from a "One Health" perspective. The gut microbiota serve as a reservoir for ARGs; however, it remains poorly understood how environmental and host genetic factors influence ARGs by affecting the gut microbiota. To elucidate this, we analyzed whole-genome resequencing data from 79 individuals of Brandt's vole in two geographic locations with different antibiotics usage, together with metabolomic data and shotgun sequencing data. A high diversity of ARGs (851 subtypes) was observed in vole's gut, with a large variation in ARG composition between individuals from Xilingol and Hulunbuir in China. The diversity and composition of ARGs were strongly correlated with variations in gut microbiota community structure. Genome-wide association studies revealed that 803 loci were significantly associated (P<5.05×10-9) with 31 bacterial species, and bipartite networks identified 906 bacterial species-ARGs associations. Structural equation modeling analysis showed that host genetic factors, air temperature, and presence of pollutants (Bisphenol A) significantly affected gut microbiota community structure, which eventually regulated the diversity of ARGs. The present study advances our understanding of the complex host-environment interactions that underlie the spread of ARGs in the natural environments.

Gut microbes, diet, and genetics as drivers of metabolic liver disease: a narrative review outlining implications for precision medicine

Metabolic dysfunction-associated steatotic liver disease (MASLD) is rapidly increasing in prevalence, impacting over a third of the global population. The advanced form of MASLD, Metabolic dysfunction-associated steatohepatitis (MASH), is on track to become the number one indication for liver transplant. FDA-approved pharmacological agents are limited for MASH, despite over 400 ongoing clinical trials, with only a single drug (resmetirom) currently on the market. This is likely due to the heterogeneous nature of disease pathophysiology, which involves interactions between highly individualized genetic and environmental factors. To apply precision medicine approaches that overcome interpersonal variability, in-depth insights into interactions between genetics, nutrition, and the gut microbiome are needed, given that each have emerged as dynamic contributors to MASLD and MASH pathogenesis. Here, we discuss the associations and molecular underpinnings of several of these factors individually and outline their interactions in the context of both patient-based studies and preclinical animal model systems. Finally, we highlight gaps in knowledge that will require further investigation to aid in successfully implementing precision medicine to prevent and alleviate MASLD and MASH.

Dietary zinc supplementation inhibits bacterial plasmid conjugation in vitro by regulating plasmid replication (rep) and transfer (tra) genes

Humans use dietary supplements for several intended effects, such as supplementing malnutrition. While these compounds have been developed for host end benefits, their ancillary impact on the gut microbiota remains unclear. The human gut has been proposed as a reservoir for the prevalent lateral transfer of antimicrobial resistance and virulence genes in bacteria through plasmid conjugation. Here, we studied the effect of dietary zinc supplements on the incidence of plasmid conjugation in vitro. Supplement effects were analyzed through standardized broth conjugation assays. The avian pathogenic Escherichia coli (APEC) strain APEC-O2-211 was a donor of the multidrug resistance plasmid pAPEC-O2-211A-ColV, and the human commensal isolate E. coli HS-4 was the plasmid-free recipient. Bacterial strains were standardized and mixed 1:1 and supplemented 1:10 with water, or zinc derived from either commercial zinc supplements or zinc gluconate reagent at varying concentrations. We observed a significant reduction in donors, recipients, and transconjugant populations in conjugations supplemented with zinc, with a dose-dependent relationship. Additionally, we observed a significant reduction (P < 0.05) in log conjugation efficiency in zinc-treated reactions. Upregulation of the mRNA for the plasmid replication initiation gene repA and the subset of transfer genes M, J, E, K, B, P, C, W, U, N, F, Q, D, I, and X was observed. Furthermore, we observed a downregulation of the conjugal propilin gene traA and the entry exclusion gene traS. This study demonstrates the effect of dietary zinc supplements on the conjugal transfer of a multidrug resistance plasmid between pathogenic and commensal bacteria during in vitro conditions.IMPORTANCEThis study identifies dietary zinc supplementation as a potential novel intervention for mitigating the emergence of multidrug resistance in bacteria, thus preventing antibiotic treatment failure and death in patients and animals. Further studies are required to determine the applicability of this approach in an in vivo model.

Regular Exercise Training Induces More Changes on Intestinal Glucose Uptake from Blood and Microbiota Composition in Leaner Compared to Heavier Individuals in Monozygotic Twins Discordant for BMI

BACKGROUND/OBJECTIVES

Obesity impairs intestinal glucose uptake (GU) (intestinal uptake of circulating glucose from blood) and alters gut microbiome. Exercise improves intestinal insulin-stimulated GU and alters microbiome. Genetics influence the risk of obesity and gut microbiome. However, the role of genetics on the effects of exercise on intestinal GU and microbiome is unclear.

METHODS

Twelve monozygotic twin pairs discordant for BMI (age 40.4 ± 4.5 years, BMI heavier 36.7 ± 6.0, leaner 29.1 ± 5.7, 8 female pairs) performed a six-month-long training intervention. Small intestine and colonic insulin-stimulated GU was studied using [18F]FDG-PET and microbiota from fecal samples with 16s rRNA.

RESULTS

Ten pairs completed the intervention. At baseline, heavier twins had lower small intestine and colonic GU (p < 0.05). Response to exercise differed between twins (p = 0.05), with leaner twins increasing colonic GU. Alpha and beta diversity did not differ at baseline. During the intervention, beta diversity changed significantly, most prominently at the mid-point (p < 0.01). Beta diversity changes were only significant in the leaner twins when the twin groups were analyzed separately. Exercise was associated with changes at the phylum level, mainly at the mid-point (pFDR < 0.05); at the genus level, several microbes increased, such as Lactobacillus and Sellimonas (pFDR < 0.05). In type 1 analyses, many genera changes were associated with exercise, and fewer, such as Lactobacillus, were also associated with dietary sugar consumption (p < 0.05).

CONCLUSIONS

Obesity impairs insulin-stimulated intestinal GU independent of genetics. Though both twin groups exhibited some microbiota changes, most changes in insulin-stimulated colon GU and microbiota were significant in the leaner twins.

Fecal microbiome analysis uncovers hidden stress effects of low stocking density on rainbow trout

BACKGROUND

Recirculating aquaculture systems can cause chronic stress in fish when stocking density is too high. However, this study tested whether low stocking density can cause fish stress. Adult rainbow trout, with an average weight of 1.517 kg (± 0.39), were subjected to low (12 kg/m3 ± 0.94) and moderate (43 kg/m3 ± 2.03) stocking densities for 24 days in a recirculating system maintained at 15 °C. At the end of the experiment, fecal microbiome analysis was carried out using a 16S rRNA amplicon sequencing. Additionally, an untargeted plasma metabolomics analysis was conducted.

RESULTS

The moderate stocking density group harboured greater numbers of commensals, such as C. somerae, R. lituseburensis, and L. plantarum. In contrast, detrimental species such as S. putrifacens and P. putida were abundant in the low-stocking density fish. Functional microbiome profiling revealed vitamin B12 salvage and synthesis in moderate stocking densities, which may support intestinal tight junction function. Additionally, vitamin B1 biosynthesis pathways were more abundant in the moderate stocking density group, which may function towards oxidative energy metabolism and protect against oxidative stress. A complementary plasma metabolomics study, although done at slightly different stocking densities and duration, confirmed the presence of blood metabolic stress markers. Elevated levels of L-lactic acid and L-Norvaline, L-Valine, and L-glutamine, indicate low stocking density fish were under stress. Furthermore, a P4HA2 stress gene biomarker confirmed the occurrence of stress in low-density fish. This study suggests that low stocking density can induce stress in fish. Moreover, moderate stocking density leads to a distinct and beneficial fecal microbiome profile.

CONCLUSION

Our study highlights the potential benefits of optimizing the stocking density of fish in recirculating aquaculture systems. This can improve fish health and welfare, promoting a more resilient fecal microbiome.

The causal relationship between gut microbiota and lower extremity deep vein thrombosis combined with pulmonary embolism

Background

Over the years, numerous studies have explored the relationship between gut microbiota and lower extremity deep vein thrombosis (LEDVT) and pulmonary embolism (PE). The present study utilized Mendelian randomization (MR) to assess the causal link between gut microbiota and LEDVT combined with PE.

Methods

Human gut microbiota genome-wide association study (GWAS) summary data from the MiBioGen consortium (n = 18,340) were utilized. Summary-level data on LEDVT (2,116 cases and 359,078 controls) and LEDVT combined with PE (4,319 cases and 356,875 controls) were obtained from the IEU Open GWAS project. MR analysis was conducted using the inverse variance weighted (IVW) method as the primary analysis. Additionally, MR-Egger, weighted median, weighted mode, and simple mode were employed as supplementary methods. Sensitivity analyses, including tests for heterogeneity and horizontal pleiotropy, were performed. Lastly, reverse MR analysis was performed.

Results

The IVW analyses revealed seven causal relationships between genetic liability in the gut microbiota and LEDVT and five causal relationships between genetic liability in the gut microbiota and LEDVT combined with PE. The intersection of these outcomes identified that the genus Butyricicoccus reduced the risk of both LEDVT and LEDVT combined with PE, while the genus Clostridium innocuum increased the risk for both conditions.

Conclusion

This study demonstrates that the gut microbiota is causally associated with LEDVT and LEDVT combined with PE. Our findings provide valuable insights into the underlying mechanisms and suggest potential avenues for further clinical investigations of these conditions.

Integrating genome- and transcriptome-wide association studies to uncover the host-microbiome interactions in bovine rumen methanogenesis

The ruminal microbiota generates biogenic methane in ruminants. However, the role of host genetics in modifying ruminal microbiota-mediated methane emissions remains mysterious, which has severely hindered the emission control of this notorious greenhouse gas. Here, we uncover the host genetic basis of rumen microorganisms by genome- and transcriptome-wide association studies with matched genome, rumen transcriptome, and microbiome data from a cohort of 574 Holstein cattle. Heritability estimation revealed that approximately 70% of microbial taxa had significant heritability, but only 43 genetic variants with significant association with 22 microbial taxa were identified through a genome-wide association study (GWAS). In contrast, the transcriptome-wide association study (TWAS) of rumen microbiota detected 28,260 significant gene-microbe associations, involving 210 taxa and 4652 unique genes. On average, host genetic factors explained approximately 28% of the microbial abundance variance, while rumen gene expression explained 43%. In addition, we highlighted that TWAS exhibits a strong advantage in detecting gene expression and phenotypic trait associations in direct effector organs. For methanogenic archaea, only one significant signal was detected by GWAS, whereas the TWAS obtained 1703 significant associated host genes. By combining multiple correlation analyses based on these host TWAS genes, rumen microbiota, and volatile fatty acids, we observed that substrate hydrogen metabolism is an essential factor linking host-microbe interactions in methanogenesis. Overall, these findings provide valuable guidelines for mitigating methane emissions through genetic regulation and microbial management strategies in ruminants.

Persistent tissue-specific resident microbiota in oysters across a broad geographical range

Marine animals often harbour complex microbial communities that influence their physiology. However, strong evidence for resident microbiomes in marine bivalves is lacking, despite their contribution to estuarine habitats and coastal economies. We investigated whether marine bivalves harbour stable, resident microorganisms in specific tissues or if their microbiomes primarily consist of transient members reflecting the environmental microbial pool. Conducting a latitudinal study of wild eastern oysters (Crassostrea virginica) along the East Coast of the United States, we aimed to identify resident microorganisms that persist across a wide geographical range. Our results revealed that microbial communities in seawater and sediment samples followed latitudinal diversity patterns driven by geographic location. In contrast, oyster-associated microbiomes were distinct from their surrounding environments and exhibited tissue-specific compositions. Notably, oyster microbiomes showed greater similarity within the same tissue type across different geographic locations than among different tissue types within the same location. This indicates the presence of tissue-specific resident microbes that persist across large geographical ranges. We identified a persistent set of resident microbiome members for each tissue type, with key microbial members consistent across all locations. These findings underscore the oyster host's role in selecting its microbiome and highlight the importance of tissue-specific microbial communities in understanding bivalve-associated microbiomes.

Causal relationship between 150 skin microbiomes and prostate cancer: insights from bidirectional mendelian randomization and meta-analysis

Background

Despite relevant research, the relationship between skin microbiomes and prostate cancer remains controversial. This study utilizes bidirectional Mendelian randomization (MR) analysis combined with meta-analysis to explore the potential link between the two.

Objective

This study aims to identify the causal relationship between 150 skin microbiomes and prostate cancer (PCa) using bidirectional Mendelian randomization (MR) and meta-analysis.

Methods

This study employed a comprehensive Bidirectional Two-sample MR analysis using publicly available genetic data to ascertain the relationship between 150 skin microbiomes and PCa. We conducted extensive sensitivity analyses, tests for heterogeneity, and assessments of horizontal pleiotropy to ensure the accuracy of our results. Subsequently, we conducted a meta-analysis to strengthen our conclusions' robustness further. Finally, we performed reverse causal verification on the positive skin microbiomes and PCa.

Results

After conducting a meta-analysis and multiple corrections of the MR analysis results, our findings reveal a correlation between Neisseria in dry skin and PCa risk, identifying it as a risk factor. The IVW result shows an Odds Ratio (OR) of 1.009 (95% Confidence Interval [CI]: 1.004-1.014, P = 0.027). Furthermore, the reverse MR analysis indicates the absence of an inverse causal relationship between the two. Apart from the identified skin microbiome, no significant associations were found between the other microbiomes and PCa.

Conclusions

The study identified a correlation between Neisseria in dry skin, one of the 150 skin microbiomes, and the risk of developing PCa, establishing it as a risk factor for increased susceptibility to PCa.

Specific gut microbiome's role in skin pigmentation: insights from SCARB1 mutants in Oujiang colour common carp

AIMS

Beyond the pivotal roles of the gut microbiome in initiating physiological processes and modulating genetic factors, a query persists: Can a single gene mutation alter the abundance of the gut microbiome community? Not only this, but the intricate impact of gut microbiome composition on skin pigmentation has been largely unexplored.

METHODS AND RESULTS

Based on these premises, our study examines the abundance of lipase-producing gut microbes about differential gene expression associated with bile acid synthesis and lipid metabolism-related blood metabolites in red (whole wild) and white (whole white wild and SCARB1-/- mutant) Oujiang colour common carp. Following the disruption of the SCARB1 gene in the resulting mutant fish with white body colour (SCARB1-/-), there is a notable decrease in the abundance of gut microbiomes (Bacillus, Staphylococcus, Pseudomonas, and Serratia) associated with lipase production. This reduction parallels the downregulation seen in wild-type white body colour fish (WW), as contrasting to the wild-type red body colour fish (WR). Meanwhile, in SCARB1-/- fish, there was a downregulation noted not only at the genetic and metabolic levels but also a decrease in lipase-producing bacteria. This consistency with WW contrasts significantly with WR. Similarly, genes involved in the bile acid synthesis pathway, along with blood metabolites related to lipid metabolism, exhibited downregulation in SCARB1-/- fish.

CONCLUSIONS

The SCARB1 knockout gene blockage led to significant alterations in the gut microbiome, potentially influencing the observed reduction in carotenoid-associated skin pigmentation. Our study emphasizes that skin pigmentation is not only impacted by genetic factors but also by the gut microbiome. Meanwhile, the gut microbiome's adaptability can be rapidly shaped and may be driven by specific single-gene variations.

Gut microbial factors predict disease severity in a mouse model of multiple sclerosis

Gut bacteria are linked to neurodegenerative diseases but the risk factors beyond microbiota composition are limited. Here we used a pre-clinical model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE), to identify microbial risk factors. Mice with different genotypes and complex microbiotas or six combinations of a synthetic human microbiota were analysed, resulting in varying probabilities of severe neuroinflammation. However, the presence or relative abundances of suspected microbial risk factors failed to predict disease severity. Akkermansia muciniphila, often associated with MS, exhibited variable associations with EAE severity depending on the background microbiota. Significant inter-individual disease course variations were observed among mice harbouring the same microbiota. Evaluation of microbial functional characteristics and host immune responses demonstrated that the immunoglobulin A coating index of certain bacteria before disease onset is a robust individualized predictor of disease development. Our study highlights the need to consider microbial community networks and host-specific bidirectional interactions when aiming to predict severity of neuroinflammation.

Ecological and genetic variables co-vary with social group identity to shape the gut microbiome of a pair-living primate

Primates exhibit diverse social systems that are intricately linked to their biology, behavior, and evolution, all of which influence the acquisition and maintenance of their gut microbiomes (GMs). However, most studies of wild primate populations focus on taxa with relatively large group sizes, and few consider pair-living species. To address this gap, we investigate how a primate's social system interacts with key environmental, social, and genetic variables to shape the GM in pair-living, red-bellied lemurs (Eulemur rubriventer). Previous research on this species suggests that social interactions within groups influence interindividual microbiome similarity; however, the impacts of other nonsocial variables and their relative contributions to gut microbial variation remain unclear. We sequenced the 16S ribosomal RNA hypervariable V4-V5 region to characterize the GM from 26 genotyped individuals across 11 social groups residing in Ranomafana National Park, Madagascar. We estimated the degree to which sex, social group identity, genetic relatedness, dietary diversity, and home range proximity were associated with variation in the gut microbial communities residing in red-bellied lemurs. All variables except sex played a significant role in predicting GM composition. Our model had high levels of variance inflation, inhibiting our ability to determine which variables were most predictive of gut microbial composition. This inflation is likely due to red-bellied lemurs' pair-living, pair-bonded social system that leads to covariation among environmental, social, and genetic variables. Our findings highlight some of the factors that predict GM composition in a tightly bonded, pair-living species and identify variables that require further study. We propose that future primate microbiome studies should simultaneously consider environmental, social, and genetic factors to improve our understanding of the relationships among sociality, the microbiome, and primate ecology and evolution.

Changes in the Firmicutes to Bacteriodetes ratio in the gut microbiome in individuals with anorexia nervosa following inpatient treatment: A systematic review and a case series

OBJECTIVE

Anorexia nervosa has the highest mortality rate among psychiatric illnesses. Current treatments remain ineffective for a large fraction of patients. This may be due to unclear mechanisms behind its development and maintenance. Studies exploring the role of the gut microbiome have revealed inconsistent evidence of dysbiosis. This article aims to investigate changes in the gut microbiome, particularly, mean differences in the Firmicutes to Bacteroidetes ratio, in adolescent and adult individuals with anorexia nervosa following inpatient treatment.

METHODS

Longitudinal studies investigating gut microbiome composition in inpatient populations of anorexia nervosa before and after treatment were systematically reviewed. Additionally, gut microbiome compositions were characterized in three acute anorexia nervosa inpatients early after admission and after 4-12 weeks of treatment.

RESULTS

Review results indicated an increase in the Firmicutes to Bacteroidetes ratio in individuals with anorexia nervosa after treatment. These however did not match values of their healthy counterparts. In the case-series samples, the reverse occurred with samples taken 4 weeks after treatment. In the patient who provided an extra sample 12 weeks after treatment, similar results to the studies included in the review were observed. Furthermore, Firmicutes to Bacteroidetes ratio values in the case-series samples were notably higher in the two patients who had chronic anorexia nervosa.

DISCUSSION

Differences in methodologies, small sample sizes, and insufficient data limited the generalizability of the outcomes of the reviewed studies. Results suggest a potentially unique microbiome signature in individuals with chronic anorexia nervosa, which may explain different outcomes in this group of patients.

Microbiota in gastrointestinal malignancies

This manuscript provides an overview of the microbiota profile associated with precancerous lesions in the esophagus, stomach, and large bowel. The critical review of the available data reveals significant variability in the methods used for microbiota profiling. This variability may affect the reliable identification of specific biological links between histologically profiled neoplastic diseases and the microbiota population. Overall, this critical review reveals significant links between microbiota communities and the different lesions within the spectrum of the oncogenetic cascade in various epidemiological contexts and anatomical districts.

The molecular basis of lactase persistence: Linking genetics and epigenetics

Lactase persistence (LP) - the genetic trait that determines the continued expression of the enzyme lactase into adulthood - has undergone recent, rapid positive selection since the advent of animal domestication and dairying in some human populations. While underlying evolutionary explanations have been widely posited and studied, the molecular basis of LP remains less so. This review considers the genetic and epigenetic bases of LP. Multiple single-nucleotide polymorphisms (SNPs) in an LCT enhancer in intron 13 of the neighbouring MCM6 gene are associated with LP. These SNPs alter binding of transcription factors (TFs) and likely prevent age-related increases in methylation in the enhancer, maintaining LCT expression into adulthood to cause LP. However, the complex relationship between the genetics and epigenetics of LP is not fully characterised, and the mode of action of methylation quantitative trait loci (meQTLs) (SNPs affecting methylation) generally remains poorly understood. Here, we examine published LP data to propose a model describing how methylation in the LCT enhancer is prevented in LP adults. We argue that this occurs through altered binding of the TF Oct-1 (encoded by the gene POU2F1) and neighbouring TFs GATA-6 (GATA6), HNF-3A (FOXA1) and c-Ets1 (ETS1) acting in concert. We therefore suggest a plausible new model for LCT downregulation in the context of LP, with wider relevance for future work on the mechanisms of other meQTLs.

Relationship between Infant Feeding and the Microbiome: Implications for Allergies and Food Intolerances

Childhood is a critical period for immune system development, which is greatly influenced by the gut microbiome. Likewise, a number of factors affect the gut microbiome composition and diversity, including breastfeeding, formula feeding, and solid foods introduction. In this regard, several studies have previously demonstrated that breastfeeding promotes a favorable microbiome. In contrast, formula feeding and the early incorporation of certain solid foods may adversely affect microbiome development. Additionally, there is increasing evidence that disruptions in the early microbiome can lead to allergic conditions and food intolerances. Thus, developing strategies to promote optimal infant nutrition requires an understanding of the relationship between infant nutrition and long-term health. The present review aims to examine the relationship between infant feeding practices and the microbiome, as well as its implications on allergies and food intolerances in infants. Moreover, this study synthesizes existing evidence on how different eating habits influence the microbiome. It highlights their implications for the prevention of allergies and food intolerances. In conclusion, introducing allergenic solid foods before six months, alongside breastfeeding, may significantly reduce allergies and food intolerances risks, being also associated with variations in gut microbiome and related complications.

'Tiny Biome Tales': A gamified review about the influence of lifestyle choices on the human microbiome

In the last two decades, new discoveries from microbiome research have changed our understanding of human health. It became evident that daily habits and lifestyle choices shape the human microbiome and ultimately determine health or disease. Therefore, we developed 'Tiny Biome Tales' (https://microbiome.gamelabgraz.at/), a science pedagogy video game designed like a scientific review based exclusively on peer-reviewed articles, to teach about the influence of lifestyle choices on the human microbiome during pregnancy, early and adult life, and related health consequences. Despite the scientific character, it can be played by a broad audience. Here, we also present a scientific assessment and showed that playing the game significantly contributed to knowledge gain. The innovative style of the 'gamified review' represents an ideal platform to disseminate future findings from microbiome research by updating existing and adding new scenes to the game.

Association between the oral microbiome and brain resting state connectivity in schizophrenia

Recent microbiome-brain axis findings have shown evidence of the modulation of microbiome community as an environmental mediator in brain function and psychiatric illness. This work is focused on the role of the microbiome in understanding a rarely investigated environmental involvement in schizophrenia (SZ), especially in relation to brain circuit dysfunction. We leveraged high throughput microbial 16s rRNA sequencing and functional neuroimaging techniques to enable the delineation of microbiome-brain network links in SZ. N = 213 SZ and healthy control subjects were assessed for the oral microbiome. Among them, 139 subjects were scanned by resting-state functional magnetic resonance imaging (rsfMRI) to derive brain functional connectivity. We found a significant microbiome compositional shift in SZ beta diversity (weighted UniFrac distance, p = 6 × 10-3; Bray-Curtis distance p = 0.021). Fourteen microbial species involving pro-inflammatory and neurotransmitter signaling and H2S production, showed significant abundance alterations in SZ. Multivariate analysis revealed one pair of microbial and functional connectivity components showing a significant correlation of 0.46. Thirty five percent of microbial species and 87.8 % of brain functional network connectivity from each component also showed significant differences between SZ and healthy controls with strong performance in classifying SZ from healthy controls, with an area under curve (AUC) = 0.84 and 0.87, respectively. The results suggest a potential link between oral microbiome dysbiosis and brain functional connectivity alteration in relation to SZ, possibly through immunological and neurotransmitter signaling pathways and the hypothalamic-pituitary-adrenal axis, supporting for future work in characterizing the role of oral microbiome in mediating effects on SZ brain functional activity.

Harnessing Artificial Intelligence in Multimodal Omics Data Integration: Paving the Path for the Next Frontier in Precision Medicine

The integration of multiomics data with detailed phenotypic insights from electronic health records marks a paradigm shift in biomedical research, offering unparalleled holistic views into health and disease pathways. This review delineates the current landscape of multimodal omics data integration, emphasizing its transformative potential in generating a comprehensive understanding of complex biological systems. We explore robust methodologies for data integration, ranging from concatenation-based to transformation-based and network-based strategies, designed to harness the intricate nuances of diverse data types. Our discussion extends from incorporating large-scale population biobanks to dissecting high-dimensional omics layers at the single-cell level. The review underscores the emerging role of large language models in artificial intelligence, anticipating their influence as a near-future pivot in data integration approaches. Highlighting both achievements and hurdles, we advocate for a concerted effort toward sophisticated integration models, fortifying the foundation for groundbreaking discoveries in precision medicine.

Composition and evolutionary characterization of the gut microbiota in pigs

The intestinal microbiota plays significant role in the physiology and functioning of host organisms. However, there is limited knowledge of the composition and evolution of microbiota-host relationships from wild ancestors to modern domesticated species. In this study, the 16S rRNA gene V3-V4 in the intestinal contents of different pig breeds was analyzed and was compared using high-throughput sequencing. This identified 18 323 amplicon sequence variants, of which the Firmicutes and Actinobacteria phyla and Bifidobacterium and Allobaculum genera were most prevalent in wild pigs (WP). In contrast, Proteobacteria and Firmicutes predominated in Chinese Shanxi Black pigs (CSB), while Firmicutes were the most prevalent phylum in Large White pigs (LW) and Iberian pigs (IB), followed by Bacteroidetes in IB and Proteobacteria in LW. At the genus level, Shigella and Lactobacillus were most prevalent in CSB and LW, while Actinobacillus and Sarcina predominated in IB. Differential gene expression together with phylogenetic and functional analyses indicated significant differences in the relative abundance of microbial taxa between different pig breeds. Although many microbial taxa were common to both wild and domestic pigs, significant diversification was observed in bacterial genes that potentially influence host phenotypic traits. Overall, these findings suggested that both the composition and functions of the microbiota were closely associated with domestication and the evolutionary changes in the host. The members of the microbial communities were vertically transmitted in pigs, with evidence of co-evolution of both the hosts and their intestinal microbial communities. These results enhance our understanding and appreciation of the complex interactions between intestinal microbes and hosts and highlight the importance of applying this knowledge in agricultural and microbiological research.

Modulation of multiple sclerosis risk and pathogenesis by the gut microbiota: Complex interactions between host genetics, bacterial metabolism, and diet

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, affecting nearly 2 million people worldwide. The etiology of MS is multifactorial: Approximately 30% of the MS risk is genetic, which implies that the remaining ~70% is environmental, with a number of factors proposed. One recently implicated risk factor for MS is the composition of the gut microbiome. Numerous case-control studies have identified changes in gut microbiota composition of people with MS (pwMS) compared with healthy control individuals, and more recent studies in animal models have begun to identify the causative microbes and underlying mechanisms. Here, we review some of these mechanisms, with a specific focus on the role of host genetic variation, dietary inputs, and gut microbial metabolism, with a particular emphasis on short-chain fatty acid and tryptophan metabolism. We put forward a model where, in an individual genetically susceptible to MS, the gut microbiota and diet can synergize as potent environmental modifiers of disease risk and possibly progression, with diet-dependent gut microbial metabolites serving as a key mechanism. We also propose that specific microbial taxa may have divergent effects in individuals carrying distinct variants of MS risk alleles or other polymorphisms, as a consequence of host gene-by-gut microbiota interactions. Finally, we also propose that the effects of specific microbial taxa, especially those that exert their effects through metabolites, are highly dependent on the host dietary intake. What emerges is a complex multifaceted interaction that has been challenging to disentangle in human studies, contributing to the divergence of findings across heterogeneous cohorts with differing geography, dietary preferences, and genetics. Nonetheless, this provides a complex and individualized, yet tractable, model of how the gut microbiota regulate susceptibility to MS, and potentially progression of this disease. Thus, we conclude that prophylactic or therapeutic modulation of the gut microbiome to prevent or treat MS will require a careful and personalized consideration of host genetics, baseline gut microbiota composition, and dietary inputs.

Causal association of juvenile idiopathic arthritis or JIA-associated uveitis and gut microbiota: a bidirectional two-sample Mendelian randomisation study

Background

The gut microbiota significantly influences the onset and progression of juvenile idiopathic arthritis (JIA) and associated uveitis (JIAU); however, the causality remains unclear. This study aims to establish a causal link between gut microbiota and JIA or JIAU.

Methods

Using publicly available genome-wide association studies (GAWS) summary data, we conducted a two-sample Mendelian randomisation (MR) analysis employing various methods, namely inverse variance weighted (IVW), simple mode, weighted mode, weighted median and MR-Egger regression methods, to assess the causal association between JIA or JIAU and gut microbiota. Sensitivity analyses, including Cochrane's Q test, MR-Egger intercept test, leave-one-out analysis and MR-PRESSO, were performed to evaluate the robustness of the MR results. Subsequently, reverse MR analysis was conducted to determine causality between gene-predicted gut microbiota abundance and JIA or JIAU.

Results

The MR analysis revealed a causal association between gut microbiota abundance variations and JIA or JIAU risk. Specifically, the increased abundance of genus Ruminococcaceae UCG013 (OR: 0.055, 95%CI: 0.006-0.103, p = 0.026) and genus Ruminococcaceae UCG003 (β: 0.06, 95%CI: 0.003-0.117, p = 0.041) correlated with an increased risk of JIA, while genus Lachnospiraceae UCG001 (OR: 0.833, 95%CI: 0.699~0.993, p = 0.042) was associated with a reduced risk of JIA, among others. Sensitivity analysis confirmed MR analysis robustness.

Conclusions

This study provides substantial evidence supporting a causal association between genetically predicted gut microbiota and JIA or JIAU. It highlights the significant role of intestinal flora in JIA or JIAU development, suggesting their potential as novel biomarkers for diagnosis and prevention. These findings offer valuable insights to mitigate the impact of JIA or JIAU.

Gut microbiome and major depressive disorder: insights from two-sample Mendelian randomization

BACKGROUND

Existing evidence suggests that alterations in the gut microbiome are closely associated with major depressive disorder (MDD). We aimed to reveal the causal relationships between MDD and various microbial taxa in the gut.

METHODS

We used the two-sample Mendelian randomization (TSMR) to explore the bidirectional causal effects between gut microbiota and MDD. The genome-wide association studies summary results of gut microbiota were obtained from two large consortia, the MibioGen consortium and the Dutch Microbiome Project, which we analyzed separately.

RESULTS

Our TSMR analysis identified 10 gut bacterial taxa that were protective against MDD, including phylum Actinobacteria, order Clostridiales, and family Bifidobacteriaceae (OR: 0.96 ∼ 0.98). Ten taxa were associated with an increased risk of MDD, including phyla Firmicutes and Proteobacteria, class Actinobacteria, and genus Alistipes (OR: 1.01 ∼ 1.09). On the other hand, MDD may decrease the abundance of 12 taxa, including phyla Actinobacteria and Firmicutes, families Bifidobacteriaceae and Defluviitaleaceae (OR: 0.63 ∼ 0.88). MDD may increase the abundance of 8 taxa, including phylum Bacteroidetes, genera Parabacteroides, and Bacteroides (OR: 1.12 ∼ 1.43).

CONCLUSIONS

Our study supports that there are mutual causal relationships between certain gut microbiota and the development of MDD suggesting that gut microbiota may be targeted in the treatment of MDD.

Microbiota, natural products, and human health: exploring interactions for therapeutic insights

The symbiotic relationship between the human digestive system and its intricate microbiota is a captivating field of study that continues to unfold. Comprising predominantly anaerobic bacteria, this complex microbial ecosystem, teeming with trillions of organisms, plays a crucial role in various physiological processes. Beyond its primary function in breaking down indigestible dietary components, this microbial community significantly influences immune system modulation, central nervous system function, and disease prevention. Despite the strides made in microbiome research, the precise mechanisms underlying how bacterial effector functions impact mammalian and microbiome physiology remain elusive. Unlike the traditional DNA-RNA-protein paradigm, bacteria often communicate through small molecules, underscoring the imperative to identify compounds produced by human-associated bacteria. The gut microbiome emerges as a linchpin in the transformation of natural products, generating metabolites with distinct physiological functions. Unraveling these microbial transformations holds the key to understanding the pharmacological activities and metabolic mechanisms of natural products. Notably, the potential to leverage gut microorganisms for large-scale synthesis of bioactive compounds remains an underexplored frontier with promising implications. This review serves as a synthesis of current knowledge, shedding light on the dynamic interplay between natural products, bacteria, and human health. In doing so, it contributes to our evolving comprehension of microbiome dynamics, opening avenues for innovative applications in medicine and therapeutics. As we delve deeper into this intricate web of interactions, the prospect of harnessing the power of the gut microbiome for transformative medical interventions becomes increasingly tantalizing.

Comparative analysis of commercially available kits for optimal DNA extraction from bovine fecal samples

In the field of metagenomic research, the choice of DNA extraction methods plays a pivotal yet often underestimated role in shaping the reliability and interpretability of microbial community data. This study delves into the impact of five commercially available DNA extraction kits on the analysis of bovine fecal microbiota. Recognizing the importance of accurate DNA extraction in elucidating microbial community dynamics, we systematically assessed DNA yield, quality, and microbial composition across these kits using 16S rRNA gene sequencing. Notably, the FastDNA spin soil kit yielded the highest DNA concentration, while significant variations in quality were observed across kits. Furthermore, differential abundance analysis revealed kit-specific biases that impacted taxa representation. Microbial richness and diversity were significantly influenced by the choice of extraction kit, with QIAamp DNA stool minikit, QIAamp Power Pro, and DNeasy PowerSoil outperforming the Stool DNA Kit. Principal-coordinate analysis revealed distinct clustering based on DNA isolation procedures, particularly highlighting the unique microbial community composition derived from the Stool DNA Kit. This study also addressed practical implications, demonstrating how kit selection influences the concentration of Gram-positive and Gram-negative bacterial taxa in samples. This research highlights the need for consideration of DNA extraction kits in metagenomic studies, offering valuable insights for researchers striving to advance the precision and depth of microbiota analyses in ruminants.

The role of animal hosts in shaping gut microbiome variation

Millions of years of co-evolution between animals and their associated microbial communities have shaped and diversified the nature of their relationship. Studies continue to reveal new layers of complexity in host-microbe interactions, the fate of which depends on a variety of different factors, ranging from neutral processes and environmental factors to local dynamics. Research is increasingly integrating ecosystem-based approaches, metagenomics and mathematical modelling to disentangle the individual contribution of ecological factors to microbiome evolution. Within this framework, host factors are known to be among the dominant drivers of microbiome composition in different animal species. However, the extent to which they shape microbiome assembly and evolution remains unclear. In this review, we summarize our understanding of how host factors drive microbial communities and how these dynamics are conserved and vary across taxa. We conclude by outlining key avenues for research and highlight the need for implementation of and key modifications to existing theory to fully capture the dynamics of host-associated microbiomes. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.

Engineered probiotics as live biotherapeutics for diagnosis and treatment of human diseases

The use of probiotics to regulate the intestinal microbiota to prevent and treat a large number of disorders and diseases has been an international research hotspot. Although conventional probiotics have a certain regulatory role in nutrient metabolism, inhibiting pathogens, inducing immune regulation, and maintaining intestinal epithelial barrier function, they are unable to treat certain diseases. In recent years, aided by the continuous development of synthetic biology, engineering probiotics with desired characteristics and functionalities to benefit human health has made significant progress. In this article, we summarise the mechanism of action of conventional probiotics and their limitations and highlight the latest developments in the design and construction of probiotics as living diagnostics and therapeutics for the detection and treatment of a series of diseases, including pathogen infections, cancer, intestinal inflammation, metabolic disorders, vaccine delivery, cognitive health, and fatty liver. Besides we discuss the concerns regarding engineered probiotics and corresponding countermeasures and outline the desired features in the future development of engineered live biotherapeutics.

Microbiome interactions with different risk factors in development of myocardial infarction

Among all non-communicable diseases, Cardiovascular Diseases (CVDs) stand as the leading global cause of mortality. Within this spectrum, Myocardial Infarction (MI) strikingly accounts for over 15 % of all deaths. The intricate web of risk factors for MI, comprising family history, tobacco use, oral health, hypertension, nutritional pattern, and microbial infections, is firmly influenced by the human gut and oral microbiota, their diversity, richness, and dysbiosis, along with their respective metabolites. Host genetic factors, especially allelic variations in signaling and inflammatory markers, greatly affect the progression or severity of the disease. Despite the established significance of the human microbiome-nutrient-metabolite interplay in associations with CVDs, the unexplored terrain of the gut-heart-oral axis has risen as a critical knowledge gap. Moreover, the pivotal role of the microbiome and the complex interplay with host genetics, compounded by age-related changes, emerges as an area of vital importance in the development of MI. In addition, a distinctive disease susceptibility and severity influenced by gender-based or ancestral differences, adds a crucial insights to the association with increased mortality. Here, we aimed to provide an overview on interactions of microbiome (oral and gut) with major risk factors (tobacco use, alcohol consumption, diet, hypertension host genetics, gender, and aging) in the development of MI and therapeutic regulation.

Probiotic formulations and gastro-intestinal diseases in the paediatric population: a narrative review

Background/Aim

Probiotics are live microbial supplements that improve the microbial balance in the host animal when administered in adequate amounts. They play an important role in relieving symptoms of many diseases associated with gastrointestinal tract, for example, in necrotizing enterocolitis (NEC), antibiotic-associated diarrhea, relapsing Clostridium difficile colitis, Helicobacter pylori infections, and inflammatory bowel disease (IBD). In this narrative review, the authors aim to evaluate the role of different probiotic formulations in treating gastrointestinal diseases in pediatric population aged 18 years or younger and highlight the main considerations for selecting probiotic formulations for use in this population.

Methodology

The authors searched PubMed and Clinicaltrials.gov from inception to 24th July 2022, without any restrictions. Using an iterative process, the authors subsequently added papers through hand-searching citations contained within retrieved articles and relevant systematic reviews and meta-analyses.

Results

The effectiveness of single-organism and composite probiotics in treating gastrointestinal disorders in pediatric patients aged 18 or under were analyzed and compared in this study. A total of 39 studies were reviewed and categorized based on positive and negative outcomes, and compared with a placebo, resulting in 25 studies for single-organism and 14 studies for composite probiotics. Gastrointestinal disorders studied included NEC, acute gastroenteritis (AGE), Acute Diarrhea, Ulcerative Colitis (UC), and others. The results show that probiotics are effective in treating various gastrointestinal disorders in children under 18, with single-organism probiotics demonstrating significant positive outcomes in most studies, and composite probiotics showing positive outcomes in all studies analyzed, with a low incidence of negative outcomes for both types.

Conclusion

This study concludes that single-organism and composite probiotics are effective complementary therapies for treating gastrointestinal disorders in the pediatric population. Hence, healthcare professionals should consider using probiotics in standard treatment regimens, and educating guardians can enhance the benefits of probiotic therapy. Further research is recommended to identify the optimal strains and dosages for specific conditions and demographics. The integration of probiotics in clinical practice and ongoing research can contribute to reducing the incidence and severity of gastrointestinal disorders in pediatric patients.

Next generation probiotics: Engineering live biotherapeutics

The population dynamics of the human microbiome have been associated with inflammatory bowel disease, cancer, obesity, autoimmune diseases, and many other human disease states. An emerging paradigm in treatment is the administration of live engineered organisms, also called next-generation probiotics. However, the efficacy of these microbial therapies can be limited by the organism's overall performance in the harsh and nutrient-limited environment of the gut. In this review, we summarize the current state of the art use of bacterial and yeast strains as probiotics, highlight the recent development of genetic tools for engineering new therapeutic functions in these organisms, and report on the latest therapeutic applications of engineered probiotics, including recent clinical trials. We also discuss the supplementation of prebiotics as a method of manipulating the microbiome and improving the overall performance of engineered live biotherapeutics.

Causal effects of immune cells in glioblastoma: a Bayesian Mendelian Randomization study

Background

Glioblastoma (GBM) is a highly malignant brain tumor, and immune cells play a crucial role in its initiation and progression. The immune system's cellular components, including various types of lymphocytes, macrophages, and dendritic cells, among others, engage in intricate interactions with GBM. However, the precise nature of these interactions remains to be conclusively determined.

Method

In this study, a comprehensive two-sample Mendelian Randomization (MR) analysis was conducted to elucidate the causal relationship between immune cell features and the incidence of GBM. Utilizing publicly available genetic data, we investigated the causal associations between 731 immune cell signatures and the risk of GBM. Subsequently, we conducted a reverse Mendelian randomization analysis to rule out reverse causation. Finally, it was concluded that there is a unidirectional causal relationship between three subtypes of immune cells and GBM. Comprehensive sensitivity analyses were employed to validate the results robustness, heterogeneity, and presence of horizontal pleiotropy. To enhance the accuracy of our results, we concurrently subjected them to Bayesian analysis.

Results

After conducting MR analyses, we identified 10 immune phenotypes that counteract glioblastoma, with the most protective being FSC-A on Natural Killer T cells (OR = 0.688, CI = 0.515-0.918, P = 0.011). Additionally, we found 11 immune cell subtypes that promote GBM incidence, including CD62L- HLA DR++ monocyte % monocyte (OR = 1.522, CI = 1.004-2.307, P = 0.048), CD4+CD8+ T cell % leukocyte (OR = 1.387, CI = 1.031-1.866, P = 0.031). Following the implementation of reverse MR analysis, where glioblastoma served as the exposure variable and the outcomes included 21 target immune cell subtypes, we discerned that only three cell subtypes (CD45 on CD33+ HLA DR+ CD14dim, CD33+ HLA DR+ Absolute Count, and IgD+ CD24+ B cell Absolute Count) exhibited a unidirectional causal association with glioblastoma.

Conclusion

Our study has genetically demonstrated the close relationship between immune cells and GBM, guiding future clinical research.

Intestinal Bacteria Fluctuating in Early-Stage Colorectal Cancer Carcinogenesis are Associated with Diet in Healthy Adults

This hospital-based, cross-sectional study aimed to explore the association between diet and fluctuating intestinal bacteria in early-stage colorectal cancer (CRC) (Atopobium parvulum, Actinomyces odontolyticus, Solobacterium moorei, and Bifidobacterium longum). Healthy participants (n = 212) who underwent total colonoscopy at National Cancer Center Hospital (Tokyo, Japan) were divided into two groups according to the relative abundance of bacteria in their feces: those in the top 25% of relative bacterial abundance as cases and the bottom 25% as controls. The participants were divided into three groups (low, medium, and high) according to their intake of food groups associated with CRC. Multivariable logistic regression analysis was conducted to estimate the association between dietary intake and higher relative abundance of bacteria. Dairy products were inversely associated with a higher relative abundance of A. parvulum, A. odontolyticus, and S. moorei, with odds ratios (high vs. low) and 95% confidence interval as follows: 0.16 (0.06-0.44), 0.25 (0.08-0.82), and 0.29 (0.11-0.78), respectively. Additionally, dietary fiber was inversely associated with a higher relative abundance of S.moorei (0.29 [0.11-0.78]). No association was observed between diet and B.longum. In conclusion, healthy adults with a higher intake of dairy products and fiber had lower odds of having a higher relative abundance of CRC-associated microbiota.

Approach to the diagnosis and management of dysbiosis

All microorganisms like bacteria, viruses and fungi that reside within a host environment are considered a microbiome. The number of bacteria almost equal that of human cells, however, the genome of these bacteria may be almost 100 times larger than the human genome. Every aspect of the physiology and health can be influenced by the microbiome living in various parts of our body. Any imbalance in the microbiome composition or function is seen as dysbiosis. Different types of dysbiosis are seen and the corresponding symptoms depend on the site of microbial imbalance. The contribution of the intestinal and extra-intestinal microbiota to influence systemic activities is through interplay between different axes. Whole body dysbiosis is a complex process involving gut microbiome and non-gut related microbiome. It is still at the stage of infancy and has not yet been fully understood. Dysbiosis can be influenced by genetic factors, lifestyle habits, diet including ultra-processed foods and food additives, as well as medications. Dysbiosis has been associated with many systemic diseases and cannot be diagnosed through standard blood tests or investigations. Microbiota derived metabolites can be analyzed and can be useful in the management of dysbiosis. Whole body dysbiosis can be addressed by altering lifestyle factors, proper diet and microbial modulation. The effect of these interventions in humans depends on the beneficial microbiome alteration mostly based on animal studies with evolving evidence from human studies. There is tremendous potential for the human microbiome in the diagnosis, treatment, and prognosis of diseases, as well as, for the monitoring of health and disease in humans. Whole body system-based approach to the diagnosis of dysbiosis is better than a pure taxonomic approach. Whole body dysbiosis could be a new therapeutic target in the management of various health conditions.

Defining predictors of responsiveness to advanced therapies in Crohn's disease and ulcerative colitis: protocol for the IBD-RESPONSE and nested CD-metaRESPONSE prospective, multicentre, observational cohort study in precision medicine

INTRODUCTION

Characterised by chronic inflammation of the gastrointestinal tract, inflammatory bowel disease (IBD) symptoms including diarrhoea, abdominal pain and fatigue can significantly impact patient's quality of life. Therapeutic developments in the last 20 years have revolutionised treatment. However, clinical trials and real-world data show primary non-response rates up to 40%. A significant challenge is an inability to predict which treatment will benefit individual patients.Current understanding of IBD pathogenesis implicates complex interactions between host genetics and the gut microbiome. Most cohorts studying the gut microbiota to date have been underpowered, examined single treatments and produced heterogeneous results. Lack of cross-treatment comparisons and well-powered independent replication cohorts hampers the ability to infer real-world utility of predictive signatures.IBD-RESPONSE will use multi-omic data to create a predictive tool for treatment response. Future patient benefit may include development of biomarker-based treatment stratification or manipulation of intestinal microbial targets. IBD-RESPONSE and downstream studies have the potential to improve quality of life, reduce patient risk and reduce expenditure on ineffective treatments.

METHODS AND ANALYSIS

This prospective, multicentre, observational study will identify and validate a predictive model for response to advanced IBD therapies, incorporating gut microbiome, metabolome, single-cell transcriptome, human genome, dietary and clinical data. 1325 participants commencing advanced therapies will be recruited from ~40 UK sites. Data will be collected at baseline, week 14 and week 54. The primary outcome is week 14 clinical response. Secondary outcomes include clinical remission, loss of response in week 14 responders, corticosteroid-free response/remission, time to treatment escalation and change in patient-reported outcome measures.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Wales Research Ethics Committee 5 (ref: 21/WA/0228). Recruitment is ongoing. Following study completion, results will be submitted for publication in peer-reviewed journals and presented at scientific meetings. Publications will be summarised at www.ibd-response.co.uk.

TRIAL REGISTRATION NUMBER

ISRCTN96296121.

Human genetic associations of the airway microbiome in chronic obstructive pulmonary disease

Little is known about the relationships between human genetics and the airway microbiome. Deeply sequenced airway metagenomics, by simultaneously characterizing the microbiome and host genetics, provide a unique opportunity to assess the microbiome-host genetic associations. Here we performed a co-profiling of microbiome and host genetics with the identification of over 5 million single nucleotide polymorphisms (SNPs) through deep metagenomic sequencing in sputum of 99 chronic obstructive pulmonary disease (COPD) and 36 healthy individuals. Host genetic variation was the most significant factor associated with the microbiome except for geography and disease status, with its top 5 principal components accounting for 12.11% of the microbiome variability. Within COPD individuals, 113 SNPs mapped to candidate genes reported as genetically associated with COPD exhibited associations with 29 microbial species and 48 functional modules (P < 1 × 10-5), where Streptococcus salivarius exhibits the strongest association to SNP rs6917641 in TBC1D32 (P = 9.54 × 10-8). Integration of concurrent host transcriptomic data identified correlations between the expression of host genes and their genetically-linked microbiome features, including NUDT1, MAD1L1 and Veillonella parvula, TTLL9 and Stenotrophomonas maltophilia, and LTA4H and Haemophilus influenzae. Mendelian randomization analyses revealed a potential causal link between PARK7 expression and microbial type III secretion system, and a genetically-mediated association between COPD and increased relative abundance of airway Streptococcus intermedius. These results suggest a previously underappreciated role of host genetics in shaping the airway microbiome and provide fresh hypotheses for genetic-based host-microbiome interactions in COPD.

Myeloid C-type lectin receptors in innate immune recognition

C-type lectin receptors (CLRs) expressed by myeloid cells constitute a versatile family of receptors that play a key role in innate immune recognition. Myeloid CLRs exhibit a remarkable ability to recognize an extensive array of ligands, from carbohydrates and beyond, and encompass pattern-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), and markers of altered self. These receptors, classified into distinct subgroups, play pivotal roles in immune recognition and modulation of immune responses. Their intricate signaling pathways orchestrate a spectrum of cellular responses, influencing processes such as phagocytosis, cytokine production, and antigen presentation. Beyond their contributions to host defense in viral, bacterial, fungal, and parasitic infections, myeloid CLRs have been implicated in non-infectious diseases such as cancer, allergies, and autoimmunity. A nuanced understanding of myeloid CLR interactions with endogenous and microbial triggers is starting to uncover the context-dependent nature of their roles in innate immunity, with implications for therapeutic intervention.

Microbiome composition as a potential predictor of longevity in rabbits

BACKGROUND

Longevity and resilience are two fundamental traits for more sustainable livestock production. These traits are closely related, as resilient animals tend to have longer lifespans. An interesting criterion for increasing longevity in rabbit could be based on the information provided by its gut microbiome. The gut microbiome is essential for regulating health and plays crucial roles in the development of the immune system. The aim of this research was to investigate if animals with different longevities have different microbial profiles. We sequenced the 16S rRNA gene from soft faeces from 95 does. First, we compared two maternal rabbit lines with different longevities; a standard longevity maternal line (A) and a maternal line (LP) that was founded based on longevity criteria: females with a minimum of 25 parities with an average prolificacy per parity of 9 or more. Second, we compared the gut microbiota of two groups of animals from line LP with different longevities: females that died/were culled with two parities or less (LLP) and females with more than 15 parities (HLP).

RESULTS

Differences in alpha and beta diversity were observed between lines A and LP, and a partial least square discriminant analysis (PLS-DA) showed a high prediction accuracy (> 91%) of classification of animals to line A versus LP (146 amplicon sequence variants (ASV)). The PLS-DA also showed a high prediction accuracy (> 94%) to classify animals to the LLP and HLP groups (53 ASV). Interestingly, some of the most important taxa identified in the PLS-DA were common to both comparisons (Akkermansia, Christensenellaceae R-7, Uncultured Eubacteriaceae, among others) and have been reported to be related to resilience and longevity.

CONCLUSIONS

Our results indicate that the first parity gut microbiome profile differs between the two rabbit maternal lines (A and LP) and, to a lesser extent, between animals of line LP with different longevities (LLP and HLP). Several genera were able to discriminate animals from the two lines and animals with different longevities, which shows that the gut microbiome could be used as a predictive factor for longevity, or as a selection criterion for these traits.

Understanding the gut microbiota by considering human evolution: a story of fire, cereals, cooking, molecular ingenuity, and functional cooperation

SUMMARYThe microbial community inhabiting the human colon, referred to as the gut microbiota, is mostly composed of bacterial species that, through extensive metabolic networking, degrade and ferment components of food and human secretions. The taxonomic composition of the microbiota has been extensively investigated in metagenomic studies that have also revealed details of molecular processes by which common components of the human diet are metabolized by specific members of the microbiota. Most studies of the gut microbiota aim to detect deviations in microbiota composition in patients relative to controls in the hope of showing that some diseases and conditions are due to or exacerbated by alterations to the gut microbiota. The aim of this review is to consider the gut microbiota in relation to the evolution of Homo sapiens which was heavily influenced by the consumption of a nutrient-dense non-arboreal diet, limited gut storage capacity, and acquisition of skills relating to mastering fire, cooking, and cultivation of cereal crops. The review delves into the past to gain an appreciation of what is important in the present. A holistic view of "healthy" microbiota function is proposed based on the evolutionary pathway shared by humans and gut microbes.

Exploring the potential effects of forest urbanization on the interplay between small mammal communities and their gut microbiota

Urbanization significantly impacts wild populations, favoring urban dweller species over those that are unable to adapt to rapid changes. These differential adaptative abilities could be mediated by the microbiome, which may modulate the host phenotype rapidly through a high degree of flexibility. Conversely, under anthropic perturbations, the microbiota of some species could be disrupted, resulting in dysbiosis and negative impacts on host fitness. The links between the impact of urbanization on host communities and their gut microbiota (GM) have only been scarcely explored. In this study, we tested the hypothesis that the bacterial composition of the GM could play a role in host adaptation to urban environments. We described the GM of several species of small terrestrial mammals sampled in forested areas along a gradient of urbanization, using a 16S metabarcoding approach. We tested whether urbanization led to changes in small mammal communities and in their GM, considering the presence and abundance of bacterial taxa and their putative functions. This enabled to decipher the processes underlying these changes. We found potential impacts of urbanization on small mammal communities and their GM. The urban dweller species had a lower bacterial taxonomic diversity but a higher functional diversity and a different composition compared to urban adapter species. Their GM assembly was mostly governed by stochastic effects, potentially indicating dysbiosis. Selection processes and an overabundance of functions were detected that could be associated with adaptation to urban environments despite dysbiosis. In urban adapter species, the GM functional diversity and composition remained relatively stable along the urbanization gradient. This observation can be explained by functional redundancy, where certain taxa express the same function. This could favor the adaptation of urban adapter species in various environments, including urban settings. We can therefore assume that there are feedbacks between the gut microbiota and host species within communities, enabling rapid adaptation.