Sex-specific associations between gut microbiota and skeletal muscle mass in a population-based study

Metagenomic Analysis Identifies Sex-Related Gut Microbial Functions and Bacterial Taxa Associated With Skeletal Muscle Mass

BACKGROUND

This study aimed to explore the association between gut microbiota functional profiles and skeletal muscle mass, focusing on sex-specific differences in a population under 65 years of age.

METHODS

Stool samples from participants were analysed using metagenomic shotgun sequencing. Skeletal muscle mass and skeletal muscle mass index (SMI) were quantified (SMI [%] = total appendage muscle mass [kg]/body weight [kg] × 100) using bioelectrical impedance analysis. Participants were categorized into SMI quartiles, and associations between gut microbiota, functional profiling and SMI were assessed by sex, adjusting for age, BMI and physical activity.

RESULTS

The cohort included 1027 participants (651 men, 376 women). In men, Escherichia coli (log2 fold change 3.08, q = 0.001), Ruminococcus_B gnavus (log2 fold change 2.89, q = 0.014) and Enterocloster sp001517625 (log2 fold change 2.47, q = 0.026) were more abundant in the lowest SMI compared to the highest SMI group. In contrast, Bifidobacterium bifidum (log2 fold change 3.13, q = 0.025) showed higher levels in the second lowest SMI group in women. Microbial pathways associated with amino acid synthesis (MET-SAM-PWY: log2 fold change 0.42; METSYN-PWY: log2 fold change 0.44; SER-GLYSYN-PWY: log2 fold change 0.20; PWY-5347: log2 fold change 0.41; P4-PWY: log2 fold change 0.53), N-acetylneuraminate degradation (log2 fold change 0.43), isoprene biosynthesis (log2 fold change 0.20) and purine nucleotide degradation and salvage (PWY-6353: log2 fold change 0.42; PWY-6608: log2 fold change 0.38; PWY66-409: log2 fold change 0.52; SALVADEHYPOX-PWY: log2 fold change 0.43) were enriched in the lowest SMI in men (q < 0.10). In women, the second lowest SMI group showed enrichment in energy-related pathways, including lactic acid fermentation (ANAEROFRUCAT-PWY: log2 fold change 0.19), pentose phosphate pathway (PENTOSE-P-PWY: log2 fold change 0.30) and carbohydrate degradation (PWY-5484: log2 fold change 0.31; GLYCOLYSIS: log2 fold change 0.29; PWY-6901: log2 fold change 0.27) (q < 0.05).

CONCLUSIONS

This study highlights sex-specific differences in gut microbiota and functional pathways associated with SMI. These findings suggest that gut microbiota may play a role in muscle health and point toward microbiota-targeted strategies for maintaining muscle mass.

Investigating the link between gut microbiome and bone mineral density: The role of genetic factors

Osteoporosis is a complex metabolic bone disease that severely undermines the quality of life and overall health of the elderly. While previous studies have established a close relationship between gut microbiome and host bone metabolism, the role of genetic factors has received less scrutiny. This research aims to identify potential taxa associated with various bone mineral density states, incorporating assessments of genetic factors. Fecal microbiome profiles from 605 individuals (334 females and 271 males) aged 55-65 from the Taizhou Imaging Study with osteopenia (n = 270, 170 women) or osteoporosis (n = 94, 85 women) or normal (n = 241, 79 women) were determined using shotgun metagenomic sequencing. The linear discriminant analysis was employed to identify differentially enriched taxa. Utilizing the Kyoto Encyclopedia of Genes and Genomes for annotation, functional pathway analysis was conducted to identify differentially metabolic pathways. Polygenic risk score for osteoporosis was estimated to represent genetic susceptibility to osteoporosis, followed by stratification and interaction analyses. Gut flora diversity did not show significant differences among various bone mineral groups. After multivariable adjustment, certain species, such as Clostridium leptum, Fusicatenibacter saccharivorans and Roseburia hominis, were enriched in osteoporosis patients. Statistically significant interactions between the polygenic risk score and taxa Roseburia faecis, Megasphaera elsdenii were observed (P for interaction = 0.005, 0.018, respectively). Stratified analyses revealed a significantly negative association between Roseburia faecis and bone mineral density in the low-genetic-risk group (β = -0.045, P < 0.05), while Turicimonas muris was positively associated with bone mineral density in the high-genetic-risk group (β = 4.177, P < 0.05) after multivariable adjustments. Functional predictions of the gut microbiome indicated an increase in pathways related to structural proteins in high-genetic-risk patients, while low-genetic-risk patients exhibited enrichment in enzyme-related pathways. This study emphasizes the association between gut microbes and bone mass, offering new insights into the interaction between genetic background and gut microbiome.

Sarcopenia Is a Risk Factor for Postoperative Complications Among Older Adults With Inflammatory Bowel Disease

BACKGROUND

Sarcopenia has been associated with adverse postoperative outcomes in older age cohorts, but has not been assessed in older adults with inflammatory bowel disease (IBD). Further, current assessments of sarcopenia among all aged individuals with IBD have used various measures of muscle mass as well as cutoffs to define its presence, leading to heterogeneous findings.

METHODS

In this single-institution, multihospital retrospective study, we identified all patients aged 60 years and older with IBD who underwent disease-related intestinal resection between 2012 and 2022. Skeletal Muscle Index (SMI) and Total Psoas Index (TPI) were measured at the superior L3 endplate on preoperative computed tomography scans and compared through receiver operating characteristic curve. We then performed multivariable logistic regression to assess risk factors associated with an adverse 30-day postoperative outcome. Our primary outcome included a 30-day composite of postoperative mortality and complications, including infection, bleeding, cardiac event, cerebrovascular accident, acute kidney injury, venous thromboembolism, reoperation, all-cause rehospitalization, and need for intensive care unit-level care.

RESULTS

A total of 120 individuals were included. Overall, 52% were female, 40% had ulcerative colitis, 60% had Crohn's disease, and median age at time of surgery was 70 years (interquartile range: 65-75). Forty percent of older adults had an adverse 30-day postoperative outcome, including infection (23%), readmission (17%), acute kidney injury (13%), bleeding (13%), intensive care unit admission (10%), cardiac event (8%), venous thromboembolism (7%), reoperation (6%), mortality (5%), and cerebrovascular accident (2%). When evaluating the predictive performance of SMI vs TPI for an adverse 30-day postoperative event, SMI had a significantly higher area under the curve of 0.66 (95% CI, 0.56-0.76) as compared to 0.58 (95% CI, 0.48-0.69) for TPI (P = .02). On multivariable logistic regression, prior IBD-related surgery (adjusted odds ratio [adjOR] 6.46, 95% CI, 1.85-22.51) and preoperative sepsis (adjOR 5.74, 95% CI, 1.36-24.17) significantly increased the odds of adverse postoperative outcomes, whereas increasing SMI was associated with a decreased risk of an adverse postoperative outcome (adjOR 0.88, 95% CI, 0.82-0.94).

CONCLUSIONS

Sarcopenia, as measured by SMI, is associated with an increased risk of postoperative complications among older adults with IBD. Measurement of SMI from preoperative imaging can help risk stratify older adults with IBD undergoing intestinal resection.

Changes in the gut microbiota of patients with sarcopenia based on 16S rRNA gene sequencing: a systematic review and meta-analysis

Introduction

Sarcopenia, an age-related disease, has become a major public health concern, threatening muscle health and daily functioning in older adults around the world. Changes in the gut microbiota can affect skeletal muscle metabolism, but the exact association is unclear. The richness of gut microbiota refers to the number of different species in a sample, while diversity not only considers the number of species but also the evenness of their abundances. Alpha diversity is a comprehensive metric that measures both the number of different species (richness) and the evenness of their abundances, thereby providing a thorough understanding of the species composition and structure of a community.

Methods

This meta-analysis explored the differences in intestinal microbiota diversity and richness between populations with sarcopenia and non-sarcopenia based on 16 s rRNA gene sequencing and identified new targets for the prevention and treatment of sarcopenia. PubMed, Embase, Web of Science, and Google Scholar databases were searched for cross-sectional studies on the differences in gut microbiota between sarcopenia and non-sarcopenia published from 1995 to September 2023 scale and funnel plot analysis assessed the risk of bias, and performed a meta-analysis with State v.15. 1.

Results

A total of 17 randomized controlled studies were included, involving 4,307 participants aged 43 to 87 years. The alpha diversity of intestinal flora in the sarcopenia group was significantly reduced compared to the non-sarcopenia group: At the richness level, the proportion of Actinobacteria and Fusobacteria decreased, although there was no significant change in other phyla. At the genus level, the abundance of f-Ruminococcaceae; g-Faecalibacterium, g-Prevotella, Lachnoclostridium, and other genera decreased, whereas the abundance of g-Bacteroides, Parabacteroides, and Shigella increased.

Discussion

This study showed that the richness of the gut microbiota decreased with age in patients with sarcopenia. Furthermore, the relative abundance of different microbiota changed related to age, comorbidity, participation in protein metabolism, and other factors. This study provides new ideas for targeting the gut microbiota for the prevention and treatment of sarcopenia.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=475887, CRD475887.

Association of skeletal muscle function, quantity, and quality with gut microbiota in Japanese adults: A cross-sectional study

AIM

The gut microbiota has emerged as a new intervention target for sarcopenia. Prior studies in humans have focused on the association between gut microbiota and skeletal muscle quantity, while the evidence on muscle function and quality is lacking. This study aimed to identify gut microbiota genera associated with skeletal muscle function, quantity, and quality in a general population of Japanese adults.

METHODS

This cross-sectional study included 164 participants aged 35-80 years, women and men recruited from urban areas of Japan. Fecal samples were collected and analyzed using 16S rRNA gene amplicon sequencing. Skeletal muscle function was measured using handgrip strength and leg extension power (LEP), while skeletal muscle mass was estimated using bioelectrical impedance analysis. Phase angle was used as a measure of skeletal muscle quality. Multivariate linear regression analysis stratified by age group was used to examine the association between the dominant genera of the gut microbiota and skeletal muscle variables.

RESULTS

A significant association was found between Bacteroides and Prevotella 9 with LEP only in the ≥60 years group. When both Bacteroides and Prevotella 9 were included in the same regression model, only Bacteroides remained consistently and significantly associated with LEP. No significant associations were observed between skeletal muscle mass, handgrip strength, and phase angle and major gut microbiota genera.

CONCLUSIONS

In this study, we observed a significant positive association between Bacteroides and leg muscle function in older adults. Further studies are required to elucidate the underlying mechanisms linking Bacteroides to lower-extremity muscle function. Geriatr Gerontol Int 2024; 24: 53-60.

The effects of race and probiotic supplementation on the intestinal microbiota of 10-km open-water swimmers

This study collected the stools of 10-km open-water swimmers after race and probiotic supplementation, and 16S rRNA sequencing and metabolomic analysis were performed to clarify their intestinal microbiota characteristics. The findings revealed a relatively high proportion of Firmicutes in all the athletes. Firmicutes in female athletes were significantly higher after probiotic supplementation. The intestinal microbiota of athletes was closely associated with the pathways of exercise against cancer, exercise against aging, exercise for improving cognition, sphingolipid metabolism and endocrine resistance. Future research should focus on the relationship between Firmicutes and Proteobacteria with super class metabolites in athletes. This report initially explored the changes in intestinal microbiota involved in metabolic pathways in athletes after race and after probiotic supplementation and provided a theoretical basis for the further improvement of the monitoring of their physical function after race and selection of nutritional strategies during exercise training.

The metabolite butyrate produced by gut microbiota inhibits cachexia-associated skeletal muscle atrophy by regulating intestinal barrier function and macrophage polarization

OBJECTIVE

Cachexia, marked by muscle atrophy, poses substantial challenges for prevention and treatment. This study delves into the unclear role of butyrate, a gut microbiota metabolite, in cachexia by examining gut microbiota and short-chain fatty acid (SCFA) profiles in human and mouse fecal samples.

METHODS

We analyzed cachexia-associated gut microbiota and SCFA profiles using 16S rRNA sequencing and metabolomic techniques. Mouse cachexia models were developed with C26 cells, and LPS was used to induce muscle cell atrophy in C2C12 cells. We evaluated butyrate's in vivo effects on intestinal health, muscle preservation, inflammation, and macrophage activity. In vitro studies focused on butyrate's influence on macrophage polarization and the subsequent effects on muscle cells.

RESULTS

Both cachexia patients and mice exhibited gut microbiota imbalances, irregular butyrate concentrations, and a decline in butyrate-producing bacteria. In vivo tests showed that butyrate counteract cachexia-induced muscle atrophy by adjusting the Akt/mTOR/Foxo3a and Fbox32/Trim63 pathways. These butyrate also bolstered intestinal barrier integrity, minimized endotoxin migration, and mitigated oxidative stress. Furthermore, butyrate curtailed inflammation and macrophage penetration in muscles. In vitro experimental results demonstrate that butyrate inhibit macrophage polarization towards the M1 phenotype and promote polarization towards the M2 phenotype. Both M1 and M2 macrophages influence the aforementioned pathways and oxidative stress, participating in the regulation of muscle cell atrophy.

CONCLUSION

Our study delineates the intricate interplay between gut microbiota dysbiosis, butyrate fluctuations, and cachexia progression. Butyrate not only reinforces the intestinal barrier but also orchestrates macrophage polarization, mitigating muscle atrophy and averting cachexia-induced muscle deterioration. Concurrently, the M1 and M2 macrophages play pivotal roles in modulating skeletal muscle cell atrophy. This highlights the potential of utilizing the gut-derived metabolite butyrate as a promising therapeutic approach for addressing cachexia-related issues.

Untailored vs. Gender- and Body-Mass-Index-Tailored Skeletal Muscle Mass Index (SMI) to Assess Sarcopenia in Advanced Head and Neck Squamous Cell Carcinoma (HNSCC)

(1) Background: Sarcopenia lasting >1 year might be considered a chronic condition in many HNSCC patients. CT-scan-derived Skeletal Muscle Mass Index (SMI) is an established surrogate of sarcopenia; yet, the cut-off reported in the literature (literature-based, lb-SMI < 43.2) is mainly based on the risk of chemoradiotherapy-induced toxicity, and the optimal value to discriminate OS is under-investigated. (2) Methods: The effect on OS of the lb-SMI cutoff was compared with an untailored OS-oriented SMI cutoff obtained in a cohort of consecutive advanced HNSCC patients treated with primary chemoradiotherapy, bio-chemotherapy or chemo-immunotherapy (cohort-specific, cs-SMI cutoff). Gender- and BMI-tailored (gt-SMI and bt-SMI) cut-offs were also evaluated. Cutoff values were identified by using the maximally selected rank statistics for OS. (3) Results: In 115 HNSCC patients, the cs-SMI cutoff was 31.50, which was lower compared to the lb-SMI reported cut-off. The optimal cut-off separately determined in females, males, overweight and non-overweight patients were 46.02, 34.37, 27.32 and 34.73, respectively. gt-SMI categorization had the highest effect on survival (p < 0.0001); its prognostic value was independent of the treatment setting or the primary location and was retained in a multivariate cox-regression analysis for OS including other HNSCC-specific prognostic factors (p = 0.0004). (4) Conclusions: A tailored SMI assessment would improve clinical management of sarcopenia in chemoradiotherapy-, bio-chemotherapy- or chemo-immunotherapy-treated HNSCC patients. Gender-based SMI could be used for prognostication in HNSCC patients.

A novel insight into the key gene signature associated with the immune landscape in the progression of sarcopenia

Sarcopenia is an age-related skeletal muscle disorder that causes falls, disability and death in the elderly, but its exact mechanism remains unknown. In this study, we merged three GEO datasets into the expression profiles of 118 samples and screened 22 differentially expressed genes (DEGs) as candidate genes. Pathway analysis demonstrated that the functional enrichment of DEGs is mainly in the cellular response to insulin stimulus, PPAR signaling pathway and other metabolism-related pathways. Then, we identified six key genes by machine learning, which were confirmed to be closely associated with sarcopenia by bioinformatics analysis. It was experimentally verified that SCD1 exhibits the most substantial alterations in the progression of sarcopenia with disturbed lipid metabolism and myosteatosis. In addition, the immune microenvironment of sarcopenia was found to be affected by these key genes, with Th17 cells down-regulated and NK cells up-regulated. Sarcopenic patients consequently presented a more significant systemic inflammatory state with higher CAR (p = 0.028) and PAR (p = 0.018). For the first time, we identified key genes in sarcopenia with high-throughput data and demonstrated that key genes can regulate the progression of sarcopenia by affecting the immune microenvironment. Among them, SCD1 may influence lipid metabolism and myosteatosis process. Screening of key genes and analyzing of immune microenvironment provide a more accurate target for treating sarcopenia.

Bioinformatic Analysis of lncRNA Mediated CeRNA Network in Intestinal Ischemia/Reperfusion Injury

INTRODUCTION

Recently, accumulating studies have reported the roles of competitive endogenous RNA (ceRNA) networks in ischemia/reperfusion (I/R) injury in several organs, including the liver, kidney, heart, brain, and intestine. However, the functions and mechanisms of long noncoding RNAs (lncRNAs)-which serve as ceRNA networks in intestinal I/R injury-remain elusive.

METHODS

RNA expression data were retrieved from the National Center for Biotechnology Information-Gene Expression Omnibus database. Differentially expressed microRNAs (miRNAs) (miDEGs) were explored between the sham and intestinal I/R injury samples. Next, targeted lncRNAs and messenger RNAs in the database were matched based on miDEGs. Hub ceRNA networks were constructed and visualized via Cytoscape. Intersection analysis was performed to screen mDEGs between two datasets. Finally, the vital nodes of the ceRNA networks were validated by quantitative PCR.

RESULTS

A total of 189 miDEGs were identified. Forty miRNAs were found to be associated with 240 predicted target genes from miRWalk 3.0. The ceRNA network was constructed with 10 miRNAs, including the 1700020114Rik/mmu-miR-7a-5p/Klf4 axis. Furthermore, the expression of lncRNA 1700020114Rik (P < 0.05) and messenger RNA Klf4 (P < 0.01) was markedly decreased in mouse models of intestinal I/R injury, whereas the expression level of mmu-miR-7a-5p was significantly increased (P < 0.05).

CONCLUSIONS

The results provide novel insights into the molecular mechanism of ceRNA networks in intestinal I/R injury and highlight the potential of the 170002700020114Rik/mmu-miR-7a-5p/Klf4 axis in the prevention and treatment of intestinal I/R injury.