Gut microbiota combined with metabolomics reveals the metabolic profile of the normal aging process and the anti-aging effect of FuFang Zhenshu TiaoZhi(FTZ) in mice

Gut Bacteria Erysipelatoclostridium and Its Related Metabolite Ptilosteroid A Could Predict Radiation-Induced Intestinal Injury

It is difficult to study the intestinal damage induced by space radiation to astronauts directly, and few prediction models exist. However, we can simulate it in patients with pelvic tumor radiotherapy (RT). Radiation-induced intestinal injury (RIII) is common in cancer patients who receieved pelvic and abdominal RT. We dynamically analyzed gut microbiota and metabolites alterations in 17 cervical and endometrial cancer patients after pelvic RT. In patients who later developed grade 2 RIII, dysbiosis of gut microbiota and metabolites were observed. Univariate analysis showed that Erysipelatoclostridium and ptilosteroid A were related to the occurrence of grade 2 RIII. Notably, a strong positive correlation between gut bacteria Erysipelatoclostridium relative abundance and gut metabolite ptilosteroid A expression was found. Furthermore, combinations of Erysipelatoclostridium and ptilosteroid A could provide good diagnostic markers for grade 2 RIII. In conclusion, gut bacteria Erysipelatoclostridium and its related metabolite ptilosteroid A may collaboratively predict RIII, and could be diagnostic biomarkers for RIII and space radiation injury.

Effects of anti-aging interventions on intestinal microbiota

Identifying ways to deal with the challenges presented by aging is an urgent task, as we are facing an aging society. External factors such as diet, exercise and drug therapy have proven to be major elements in controlling healthy aging and prolonging life expectancy. More recently, the intestinal microbiota has also become a key factor in the anti-aging process. As the intestinal microbiota changes with aging, an imbalance in intestinal microorganisms can lead to many age-related degenerative diseases and unhealthy aging. This paper reviews recent research progress on the relationship between intestinal microorganisms and anti-aging effects, focusing on the changes and beneficial effects of intestinal microorganisms under dietary intervention, exercise and drug intervention. In addition, bacteriotherapy has been used to prevent frailty and unhealthy aging. Most of these anti-aging approaches improve the aging process and age-related diseases by regulating the homeostasis of intestinal flora and promoting a healthy intestinal environment. Intervention practices based on intestinal microorganisms show great potential in the field of anti-aging medicine.

Crosstalk between gut microbiota and host lipid metabolism in a mouse model of alcoholic liver injury by chronic baijiu or ethanol feeding

A growing body of evidence highlights the important role of gut microbiota and host metabolism, particularly for lipid metabolism, in the development and progression of alcoholic liver disease (ALD). However, the effects of fermented alcoholic beverages on gut microbiota and host lipid metabolism remain under-investigated. Moreover, the crosstalk between gut microbiota and host lipid metabolism is still unclear in experimental ALD. Baijiu is a traditional Chinese alcoholic beverage. It contains large amounts of small molecule bioactive compounds in addition to a significant amount of ethanol (EtOH). In this study, we showed that baijiu caused lower degrees of liver injury than pure EtOH as revealed by phenotypic, biochemical and histologic analyses. Furthermore, baijiu and EtOH gavage resulted in different gut microbiota structures. Specifically, the baijiu group had a significantly higher abundance of Ruminococcus, Oscillospira, Mucispirillum, Bilophila, Parabacteroides and Odoribacter and a lower abundance of Helicobacter and Prevotella than that of the EtOH group. Using a targeted metabolomics approach, we also observed a greater than 19% increase of total hepatic free fatty acids (FFAs) after baijiu feeding and a 33% increase of hepatic FFAs after EtOH feeding. Baijiu feeding significantly increased total hepatic mono-unsaturated FAs (MUFAs). In contrast, polyunsaturated fatty acids (PUFAs), MUFAs and saturated FAs were significantly increased by EtOH feeding. Finally, Spearman's rank correlation showed that the increased levels of FFAs (mainly C20 and C22 unsaturated FAs) significantly correlated with key different gut microbiota, including a positive correlation with Desulfovibrio, Maihella, Helicobacter, Acholeplasma, Parasutterella, Prevotella, AF12 and Alistipes, and a negative correlation with Dorea, Olsenella, Adlercreutzia and Akkermansia. Our results suggest that compounds in baijiu attenuated the development of ALD and thus provided supporting evidence that the host-gut microbiota metabolic interactions play an important role in the development of ALD.

The Impacts of Short-Term NMN Supplementation on Serum Metabolism, Fecal Microbiota, and Telomere Length in Pre-Aging Phase

Aging is a natural process with concomitant changes in the gut microbiota and associate metabolomes. Beta-nicotinamide mononucleotide, an important NAD+ intermediate, has drawn increasing attention to retard the aging process. We probed the changes in the fecal microbiota and metabolomes of pre-aging male mice (C57BL/6, age: 16 months) following the oral short-term administration of nicotinamide mononucleotide (NMN). Considering the telomere length as a molecular gauge for aging, we measured this in the peripheral blood mononuclear cells (PBMC) of pre-aging mice and human volunteers (age: 45-60 years old). Notably, the NMN administration did not influence the body weight and feed intake significantly during the 40 days in pre-aging mice. Metabolomics suggested 266 upregulated and 58 downregulated serum metabolites. We identified 34 potential biomarkers linked with the nicotinamide, purine, and proline metabolism pathways. Nicotinamide mononucleotide significantly reduced the fecal bacterial diversity (p < 0.05) with the increased abundance of Helicobacter, Mucispirillum, and Faecalibacterium, and lowered Akkermansia abundance associated with nicotinamide metabolism. We propose that this reshaped microbiota considerably lowered the predicated functions of aging with improved immune and cofactors/vitamin metabolism. Most notably, the telomere length of PBMC was significantly elongated in the NMN-administered mice and humans. Taken together, these findings suggest that oral NMN supplementation in the pre-aging stage might be an effective strategy to retard aging. We recommend further studies to unravel the underlying molecular mechanisms and comprehensive clinical trials to validate the effects of NMN on aging.

Integration of Gut Microbiota and Metabolomics for Chinese Medicines Research: Opportunities and Challenges

Chinese medicines (CM) are gaining more attentions from all over the world. However, there are a large body of questions to be answered because of the chemical complexity of CM and intricate molecular reactions within human body. In recent years, gut microbiota and metabolomics have emerged as two cynosures in deciphering the mechanisms of how our body is functioning. Since gut microbiota and host is a closely interrelated system, paying attention only to gut microbiota or metabolites may omit the interplays among CM, gut microbiota, and hosts. To systemically study these interplays, a network understanding of CM components, gut microbiota, metabolites of gut microbiota, metabolites in human body is necessary. Although there are some obstacles impeding the application of this integrative approach, the potential areas for implementation of the integrative approach is vast. These areas include, but not limited to, elucidating the mechanisms of CM at system level, screening bioactive compounds in CM, and guiding quality control of CM.

Ubiquinol-cytochrome c reductase core protein 1 contributes to cardiac tolerance to acute exhaustive exercise

Ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) is an indispensable component of mitochondrial complex III. It plays a key role in cardioprotection and maintaining mitochondrion function. However, the exact role of UQCRC1 in maintaining cardiac function has not been reported by in vivo models. Also, the exact biological functions of UQCRC1 are far from fully understood. UQCRC1^+/- mice had decreased both mRNA and protein expression of UQCRC1 in the left ventricular myocardia, and these mice had reduced tolerance to acute exhaustive exercise including decreased time and distance with higher apoptosis rate, higher expression level of cleaved CASPASE 3, and higher ratio of cleaved PARP1 to full-length PARP1. Moreover, UQCRC1 knockdown led to increased LV interventricular septal thicknesses both at systole and diastole, as well as decreased LV volume both at end-systole and end-diastole. Finally, UQCRC1 gene disruption resulted in mitochondrial vacuolation, fibril disarrangement, and more severe morphological and structural changes in mitochondria after acute exhaustive exercise. In conclusion, UQCRC1 contributes to cardiac tolerance to acute exhaustive exercise in mice, and it may be an essential component of complex III, playing a crucial role in maintaining cardiac functions.

FTZ Ameliorates Diabetic Cardiomyopathy by Inhibiting Inflammation and Cardiac Fibrosis in the Streptozotocin-Induced Model

Background

The pathogenesis and clinical features of diabetic cardiomyopathy (DCM) have been well studied in the past decade; however, effective approaches to prevent and treat this disease are limited. Fufang Zhenzhu Tiaozhi (FTZ) formula, a traditional Chinese prescription, is habitually used to treat dyslipidemia and diabetes. Recently, several studies have reported the therapeutic effects of FTZ on cardiovascular diseases. However, the effects of FTZ on DCM have not yet been fully elucidated. This study investigated the effects of FTZ on DCM and determined the mechanisms underlying its efficacy.

Methods

Diabetes was induced in mice by intraperitoneal injection of streptozotocin; the mice were randomly divided into a control group (Con), diabetes group (DCM), and diabetes-treated with FTZ (DCM + FTZ). Myocardial structural alterations, fibrosis biomarkers, and inflammation were observed. Besides, the potential targets and their related signaling pathways were analyzed using network pharmacology and further verified by Western blot.

Results

Diabetic mice showed significant body weight loss, hyperglycemia, and excessive collagen content in the cardiac tissue, while serum and myocardial inflammatory factors significantly increased. Nerveless, treatment with FTZ for 1 month significantly improved body weight, attenuated hyperglycemia, and alleviated diabetes-associated myocardial structure and function abnormalities. Furthermore, the serum levels of interleukin 12 (IL-12) and chemokine (C–C motif) ligand 2 (CCL2) as well as the mRNA levels of cardiac IL-12, IL-6, and C–C motif chemokine receptor 2 (Ccr2) reduced after FTZ treatment. Additionally, a total of 67 active compounds and 76 potential targets related to DCM were analyzed. Pathway and functional enrichment analyses showed that FTZ mainly regulates inflammation-related pathways, including MAPK and PI3K-AKT signaling pathways. Further investigation revealed that the activities of STAT3, AKT, and ERK were augmented in diabetic hearts but decreased in FTZ-treated cardiac tissues.

Conclusion

Our results suggest that FTZ exhibits therapeutic properties against DCM by ameliorating hyperglycemia-induced inflammation and fibrosis via at least partial inhibition of AKT, ERK, and STAT3 signaling pathways.

Gut Microbiota Dysbiosis Is a Crucial Player for the Poor Outcomes for COVID-19 in Elderly, Diabetic and Hypertensive Patients

A new infectious disease, named COVID-19, caused by the coronavirus associated to severe acute respiratory syndrome (SARS-CoV-2) has become pandemic in 2020. The three most common pre-existing comorbidities associated with COVID-19-related death are elderly, diabetic, and hypertensive people. A common factor among these risk groups for the outcome of death in patients infected with SARS-CoV-2 is dysbiosis, with an increase in the proportion of bacteria with a pro-inflammatory profile. Due to this dysbiosis, elderly, diabetic, and hypertensive people present a higher propensity to mount an inflammatory environment in the gut with poor immune editing, culminating in a weakness of the intestinal permeability barrier and high bacterial product translocation to the bloodstream. This scenario culminates in a low-grade, persistent, and systemic inflammation. In this context, we propose here that high circulating levels of bacterial products, like lipopolysaccharide (LPS), can potentiate the SARS-CoV-2-induced cytokines, including IL-6, being crucial for development of the cytokine storm in the severe form of the disease. A better understanding on the possible correlation between gut dysbiosis and poor outcomes observed in elderly, diabetic, and hypertensive people can be useful for the development of new therapeutic strategies based on modulation of the gut microbiota.

Molecular mechanism of Fufang Zhenzhu Tiaozhi capsule in the treatment of type 2 diabetes mellitus with nonalcoholic fatty liver disease based on network pharmacology and validation in minipigs

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Zhenzhu Tiaozhi formula (FTZ) of which a patented preparation of Chinese herbal medicine has been well documented with significant clinical curative effect for hyperglycemia and hyperlipidemia. Because of the complexity of the chemical constituents of Chinese herbal formulas, the holistic pharmacological mechanism of FTZ acting on type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD) remains unclear.

AIM OF THE STUDY

To investigate the pharmacological efficacy and mechanism of FTZ in the treatment of T2DM accompanied by NAFLD.

MATERIALS AND METHODS

Network pharmacology and validation in minipigs were used in this study. First, potential bioactive compounds of FTZ were identified by the traditional Chinese medicine system pharmacology technology platform (TCMSP). Then, targets of compounds were gathered using DrugBank, SwissTargetPrediction and TCMSP, while targets for T2DM and NAFLD were collected from CTD (compounds-targets-diseases network) and GeneCards. Common targets were defined as direct therapeutic targets acting on T2DM with NAFLD. In addition, crucial targets were chosen by the protein-protein interaction (PPI) network and contribution to compound-therapeutic targets in T2DM with the NAFLD network. Furthermore, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyze the metabolism-related signaling pathways affected by FTZ. Candidate patterns selected by network pharmacology were tested in the minipigs model of T2DM with NAFLD. Measurements of triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting insulin (FINS) and fasting blood glucose (FBG) in the blood and the expression levels of proteins, including PI3K-AKT and HIF-1α, in the livers of the minipigs were followed by the administration of FTZ.

RESULTS

A total of 116 active compounds and 82 potential targets related to T2DM and NAFLD were found. Pathway and functional enrichment analysis showed that FTZ mainly regulates metabolism-related pathways, including PI3K-AKT, HIF-1α, TNFα and MAPK. Animal experiments showed that FTZ treatment significantly reduced the serum levels of TG, TC, LDL-C and FBG, increased serum levels of HDL-C, ameliorated systemic insulin resistance (IR), and attenuated liver damage in minipigs with T2DM and NAFLD. FTZ treatment has an obviously favorable influence on hepatic steatosis and liver lipid accumulation in the histopathologic features of HE, Oil red O staining, and electron microscopy. Mechanistically, FTZ improved liver metabolism by increasing the phosphorylation of PI3K-AKT and decreasing the expression of HIF-1α.

CONCLUSION

Network pharmacology was supported by experimental studies, which indicated that FTZ has demonstrated therapeutic benefits in T2DM and NAFLD by regulating the PI3K-AKT and HIF-1α signaling pathways.

Microbiome-Metabolomics Reveals Endogenous Alterations of Energy Metabolism by the Dushen Tang to Attenuate D-Galactose-Induced Memory Impairment in Rats

Aging affects the brain function in elderly individuals, and Dushen Tang (DST) is widely used for the treatment of senile diseases. In this study, the protective effect of DST against memory impairment was evaluated through the Morris water maze (MWM) test and transmission electron microscopy (TEM). A joint analysis was also performed using LC-MS metabolomics and the microbiome. The MWM test showed that DST could significantly improve the spatial memory and learning abilities of rats with memory impairment, and the TEM analysis showed that DST could reduce neuronal damage in the hippocampus of rats with memory impairment. Ten potential biomarkers involving pyruvate metabolism, the synthesis and degradation of ketone bodies, and other metabolic pathways were identified by the metabolomic analysis, and it was found that 3-hydroxybutyric acid and lactic acid were involved in the activation of cAMP signaling pathways. The 16S rDNA sequencing results showed that DST could regulate the structure of the gut microbiota in rats with memory impairment, and these effects were manifested as changes in energy metabolism. These findings suggest that DST exerts a good therapeutic effect on rats with memory impairment and that this effect might be mainly achieved by improving energy metabolism. These findings might lead to the potential development of DST as a drug for the treatment of rats with memory impairment.

Anti-aging effects of a functional food via the action of gut microbiota and metabolites in aging mice

Wushen (WS) is a mixed food containing 55 natural products that is beneficial to human health. This study aimed to reveal the preventive effect of WS on aging via a combined analysis of gut microbiome and metabolome. Senescence-accelerated mouse prone 8 (SAMP8) mice were used as aging model and senescence-accelerated mouse resistant 1 (SAMR1) mice as control. The mice were fed four diet types; control diet (for SAMR1 mice), standard diet (for SAMP8 mice, as SD group), WS diet, and fecal microbiota transplantation (FMT; transplanted from aging-WS mice). Our results showed that the weight, food intake, neurological function, and general physical conditions significantly improved in WS-fed mice compared to those fed with SD. The CA1 hippocampal region in WS-fed aged mice showed fewer shriveled neurons and increased neuronal layers compared to that of the SD group. WS-fed mice showed a decrease in malondialdehyde and an increase in superoxide dismutase levels in the brain; additionally, IL-6 and TNF-α levels significantly decreased, whereas IL-2 levels and the proportion of lymphocytes, CD3+CD8+ T, and CD4+IFNγ+T cells increased in WS-fed mice. After fed with WS, the abundance of Ruminococcus and Butyrivibrio markedly increased, whereas Lachnoclostridium and Ruminiclostridium significantly decreased in the aging mice. In addition, 887 differentially expressed metabolites were identified in fecal samples, among these, Butyrivibrio was positively correlated with D-glucuronic acid and Ruminococcus was positively associated with 5-acetamidovalerate. These findings provide mechanistic insight into the impact of WS on aging, and WS may be a valuable diet for preventing aging.

FTZ attenuates liver steatosis and fibrosis in the minipigs with type 2 diabetes by regulating the AMPK signaling pathway

Fufang Zhenzhu Tiaozhi formula (FTZ), a preparation of Chinese herbal medicine, has various pharmacological properties, such as hypoglycemic, hypolipidemic, anticoagulant, and anti-inflammatory activities. Hepatocyte apoptosis is a marker of nonalcoholic steatohepatitis (NASH) and contributes to liver injury, fibrosis, and inflammation. Given the multiple effects of FTZ, we investigated whether FTZ can be a therapeutic agent for NASH and its mechanism. In the present study, we observed that FTZ treatment had an obviously favorable influence on hepatic steatosis and fibrosis in the histopathologic features of type 2 diabetes mellitus (T2DM) and coronary heart disease (CHD) with NASH minipigs. In addition, immunohistochemical analysis showed increased expression of the fibrotic marker α-smooth muscle actin (α-SMA), and a TUNEL assay revealed increased apoptotic positive hepatic cells in the liver tissues of the model group. Furthermore, FTZ administration reduced the increased expression of α-SMA, and FTZ inhibited apoptosis by affecting Bcl-2/Bax and cleaved caspase-3 expression. Mechanistically, our data suggested that FTZ treatment attenuated hepatic steatosis and fibrosis via the adenosine monophosphate-activated protein kinase (AMPK) pathway. In vitro studies showed that FTZ also attenuated intracellular lipid accumulation in HepG2 cells exposed to palmitic acid (PA) and oleic acid (OA). FTZ upregulated the expression levels of P-AMPK and BCL-2 and downregulated BAX. The changes induced by FTZ were reversed by Compound C, an inhibitor of AMPK. In conclusion, FTZ attenuated NASH by ameliorating steatosis and hepatocyte apoptosis, which is attributable to the regulation of the AMPK pathway.

Distinctive gut microbial dysbiosis between chronic alcoholic fatty liver disease and metabolic-associated fatty liver disease in mice

The gut microbiota, which may affect normal physiological and biochemical functions, has an important role in the development of human liver diseases. The aim of the present study was to investigate differences in the gut microbiota between chronic alcoholic fatty liver disease (AFLD) and metabolic-associated fatty liver disease (MAFLD). AFLD was induced by chronic alcohol administration and MAFLD was induced by a Western-style diet in C57BL/6 mice. After 8 weeks, the levels of plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (TC), lipopolysaccharide (LPS), tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β and IL-10 were assessed and H&E staining of mouse liver tissue was performed. High-throughput sequencing of 16S ribosomal DNA from the intestinal contents was used to analyze the different effects of AFLD and MAFLD on the gut microbiota. Differences in the gut microbiota composition were assessed by the t-test. The results revealed increases in LPS, ALT, AST, TG, IL-1β and TNF-α in the AFLD group. Compared with those in the MAFLD control group, the MAFLD group exhibited increased plasma ALT, TG, TC, IL-6, IL-1β and TNF-α levels and decreased plasma IL-10 levels. In addition, the α- and β-diversities revealed that the AFLD and MAFLD groups exhibited obvious changes in the gut structure (with an increase in abundance in the AFLD group and a decrease in abundance in the MAFLD group). In comparison to the AFLD control group, Enterococcaceae were the most abundant bacteria at the family level and Enterococcus and Streptococcus were the most abundant bacteria at the genus level in the AFLD group. However, in the MAFLD group, Lachnospiraceae was the most abundant at the family level, with increases in Erysipelatoclostridium, Gordonibacter and Streptococcus at the genus level and a decrease in the genus Bifidobacterium. In conclusion, the present study confirmed that the AFLD and MAFLD groups harbored differences in the gut microbiota. The marked differences in the gut microbiota at the family and genus levels may contribute to the development process of FLD.

Gut Microbiota Combined With Metabolomics Reveals the Repeated Dose Oral Toxicity of β-Cyclodextrin in Mice

Βeta-cyclodextrin (β-CD) with a hydrophobic cavity enables the formation of inclusion complexes with organic molecules. The formation of host–guest complexes makes the application of β-CD popular in many fields, but their interaction with organisms is poorly understood. In the present study, the effect of β-CD on gut microbiota (16S rRNA gene sequencing), serum metabolites (gas chromatography–mass spectrometry platform), and their correlation (Pearson correlation analysis) was investigated after 14 days repeated oral exposure in mice. β-CD did not significantly affect the α-diversity indexes, including Richness, Chao1, Shannon and Simpson indexes, but disturbed the structure of the gut bacteria according to the result of principal component analysis (PCA). After taxonomic assignment, 1 in 27 phyla, 2 in 48 classes, 3 in 107 orders, 6 in 192 families, and 8 in 332 genera were significantly different between control and β-CD treated groups. The serum metabolites were significantly changed after β-CD treatment according to the result of unsupervized PCA and supervised partial least squares-discriminant analysis (PLS-DA). A total of 112 differential metabolites (89 downregulated and 23 upregulated) were identified based on the VIP >1 from orthogonal PLS-DA and p <0.05 from Student’s t-test. The metabolic pathways, including ABC transporters, pyrimidine metabolism, purine metabolism, glucagon signaling pathway, insulin signaling pathway, and glycolysis/gluconeogenesis, were enriched by KEGG pathway analysis. Our study provides a general observation of gut microbiota, serum metabolites and their correlation after exposure to β-CD in mice, which will be helpful for future research and application of β-CD.

Gut dysbiosis and age-related neurological diseases; an innovative approach for therapeutic interventions

The gut microbiota is a complex ecosystem of bacteria, fungi, and viruses that acts as a critical regulator in microbial, metabolic, and immune responses in the host organism. Imbalances in the gut microbiota, termed "dysbiosis," often induce aberrant immune responses, which in turn disrupt the local and systemic homeostasis of the host. Emerging evidence has highlighted the importance of gut microbiota in intestinal diseases, and more recently, in age-related central nervous systems diseases, for example, stroke and Alzheimer's disease. It is now generally recognized that gut microbiota significantly influences host behaviors and modulates the interaction between microbiota, gut, and brain, via the "microbiota-gut-brain axis." Several approaches have been utilized to reduce age-related dysbiosis in experimental models and in clinical studies. These include strategies to manipulate the microbiome via fecal microbiota transplantation, administration of prebiotics and probiotics, and dietary interventions. In this review, we explore both clinical and preclinical therapies for treating age-related dysbiosis.

Growth Hormone Deficiency and Excess Alter the Gut Microbiome in Adult Male Mice

The gut microbiome has been implicated in host metabolism, endocrinology, and pathophysiology. Furthermore, several studies have shown that gut bacteria impact host growth, partially mediated through the growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis. Yet, no study to date has examined the specific role of GH on the gut microbiome. Our study thus characterized the adult gut microbial profile and intestinal phenotype in GH gene-disrupted (GH-/-) mice (a model of GH deficiency) and bovine GH transgenic (bGH) mice (a model of chronic, excess GH action) at 6 months of age. Both the GH-/- and bGH mice had altered microbial signatures, in opposing directions at the phylum and genus levels. For example, GH-/- mice had significantly reduced abundance in the Proteobacteria, Campylobacterota, and Actinobacteria phyla, whereas bGH mice exhibited a trending increase in those phyla compared with respective controls. Analysis of maturity of the microbial community demonstrated that lack of GH results in a significantly more immature microbiome while excess GH increases microbial maturity. Several common bacterial genera were shared, although in opposing directions, between the 2 mouse lines (e.g., decreased in GH-/- mice and increased in bGH mice), suggesting an association with GH. Similarly, metabolic pathways like acetate, butyrate, heme B, and folate biosynthesis were predicted to be impacted by GH. This study is the first to characterize the gut microbiome in mouse lines with altered GH action and indicates that GH may play a role in the growth of certain microbiota thus impacting microbial maturation and metabolic function.