Metabolic role of lactobacilli in weight modification in humans and animals

Analysis of the Bacterial and Host Proteins along and across the Porcine Gastrointestinal Tract

Pigs are among the most important farm animals worldwide and research to optimize their feed efficiency and improve their welfare is still in progress. The porcine intestinal microbiome is so far mainly known from sequencing-based studies. Digesta and mucosa samples from five different porcine gastrointestinal tract sections were analyzed by metaproteomics to obtain a deeper insight into the functions of bacterial groups with concomitant analyses of host proteins. Firmicutes (Prevotellaceae) dominated mucosa and digesta samples, followed by Bacteroidetes. Actinobacteria and Proteobacteria were much higher in abundance in mucosa compared to digesta samples. Functional profiling reveals the presence of core functions shared between digesta and mucosa samples. Protein abundances of energy production and conversion were higher in mucosa samples, whereas in digesta samples more proteins were involved in lipid transport and metabolism; short-chain fatty acids production were detected. Differences were also highlighted between sections, with the small intestine appearing more involved in carbohydrate transport and metabolism than the large intestine. Thus, this study produced the first functional analyses of the porcine GIT biology, discussing the findings in relation to expected bacterial and host functions.

Abnormality in Maternal Dietary Calcium Intake During Pregnancy and Lactation Promotes Body Weight Gain by Affecting the Gut Microbiota in Mouse Offspring

SCOPE

To investigate the effects of calcium status in early life on adult body weight and the underlying mechanisms involved in gut microbiota and related lipid metabolism.

METHODS AND RESULTS

Three to four-week-old C57BL/6J female mice were fed diets with normal, insufficient, and excessive calcium respectively throughout pregnancy and lactation. The weaning male pups were fed with a high-fat diet for 16 weeks, with a normal-fat diet to the normal calcium group as control. The offspring fecal microbiota was analyzed by 16S rRNA high-throughput sequencing, and mRNA expressions of genes were determined by the real-time RT-PCR. Maternal insufficient or excessive calcium intake exacerbated offspring obesity, with expressional changes in the Fasn, Acc1, LPL, Fiaf, and PPAR-α genes in the liver or fat. The dysbiosis in gut microbiota in obese offspring was exacerbated by maternal imbalanced calcium intake, with increased Firmicutes and decreased Bacteroidetes in calcium insufficiency, and decreased Verrucomicrobia in calcium excess. Several genera, including Bacteroides, were reduced, and Lachnospiraceae and Lactobacillus were increased by maternal insufficient or excessive calcium intake.

CONCLUSION

Imbalance in maternal calcium intake promotes body weight gain in offspring, which may be mediated by calcium's modulation on the gut microbiota and lipid metabolism.

Gut microbiota as important modulator of metabolism in health and disease

The human gastrointestinal tract colonizes a large number of microbial microflora, forms a host-microbiota co-metabolism structure with the host to participate in various metabolic processes in the human body, and plays a major role in the host immune response. In addition, the dysbiosis of intestinal microbial homeostasis is closely related to many diseases. Thus, an in-depth understanding of the relationship between them is of importance for disease pathogenesis, prevention and treatment. The combined use of metagenomics, transcriptomics, proteomics and metabolomics techniques for the analysis of gut microbiota can reveal the relationship between microbiota and the host in many ways, which has become a hot topic of analysis in recent years. This review describes the mechanism of co-metabolites in host health, including short-chain fatty acids (SCFA) and bile acid metabolism. The metabolic role of gut microbiota in obesity, liver diseases, gastrointestinal diseases and other diseases is also summarized, and the research methods for multi-omics combined application on gut microbiota are summarized. According to the studies of the interaction mechanism between gut microbiota and the host, we have a better understanding of the use of intestinal microflora in the treatment of related diseases. It is hoped that the gut microbiota can be utilized to maintain human health, providing a reference for future research.

Repertoire of the gut microbiota from stomach to colon using culturomics and next-generation sequencing

BACKGROUND

Most studies on the human microbiota have analyzed stool samples, although a large proportion of the absorption of nutrients takes place in upper gut tract. We collected samples from different locations along the entire gastrointestinal tract from six patients who had simultaneously undergone upper endoscopy and colonoscopy, to perform a comprehensive analysis using culturomics with matrix assisted laser desorption ionisation - time of flight (MALDI-TOF) identification and by metagenomics targeting the 16S ribosomal ribonucleic acid (rRNA) gene.

RESULTS

Using culturomics, we isolated 368 different bacterial species, including 37 new species. Fewer species were isolated in the upper gut: 110 in the stomach and 106 in the duodenum, while 235 were isolated from the left colon (p < 0.02). We isolated fewer aero-intolerant species in the upper gut: 37 from the stomach and 150 from the left colon (p < 0.004). Using metagenomics, 1,021 species were identified. The upper gut microbiota was revealed to be less rich than the lower gut microbiota, with 37,622 reads from the stomach, 28,390 from the duodenum, and 79,047 from the left colon (p < 0.009). There were fewer reads for aero-intolerant species in the upper gut (8,656 in the stomach, 5,188 in the duodenum and 72,262 in the left colon, p < 0.02). Patients taking proton pump inhibitors (PPI) were then revealed to have a higher stomach pH and a greater diversity of species in the upper digestive tract than patients not receiving treatment (p < 0.001).

CONCLUSION

Significant modifications in bacterial composition and diversity exist throughout the gastrointestinal tract. We suggest that the upper gut may be key to understanding the relationship between the gut microbiota and health.

Adipose tissue inflammation and metabolic syndrome. The proactive role of probiotics

PURPOSE

The first part of this review focuses on the role of cells and molecules of adipose tissue involved in metabolic syndrome-induced inflammation and in the maintenance of this pathology. In the second part of the review, the potential role of probiotics-modulating metabolic syndrome-related inflammatory components is summarized and discussed.

METHODS

The search for the current scientific literature was carried out using ScienceDirect, PubMed, and Google Scholar search engines. The keywords used were: metabolic syndrome, obesity, insulin resistant, adipose tissue, adipose tissue inflammation, chronic low-grade inflammation, immune cells, adipokines, cytokines, probiotics, and gut microbiota.

RESULTS AND CONCLUSIONS

Chronic low-grade inflammation that characterized metabolic syndrome can contribute to the development of the metabolic dysfunctions involved in the pathogenesis of its comorbidities. Adipose tissue is a complex organ that performs metabolic and immune functions. During metabolic syndrome, an imbalance in the inflammatory components of adipose tissue (immune cells, cytokines, and adipocytokines), which shift from an anti-inflammatory to a pro-inflammatory profile, can provoke metabolic syndrome linked complications. Further knowledge concerning the immune function of adipose tissue may contribute to finding better alternatives for the treatment or prevention of such disorders. The control of inflammation could result in the management of many of the pathologies related to metabolic syndrome. Due to the strong evidence that gut microbiota composition plays a role modulating the body weight, adipose tissue, and the prevalence of a low-grade inflammatory status, probiotics emerge as valuable tools for the prevention of metabolic syndrome and health recovery.

The emerging connections between IGF1, the intestinal microbiome, Lactobacillus strains and bone growth

In most animal species, postnatal growth is controlled by conserved insulin/insulin-like growth factor (IGF) signaling. In mammals, juvenile growth is characterized by a longitudinal bone growth resulting from the ossification of the growth plate. This ossification is under IGF1 influence through endocrine and paracrine mechanisms. Moreover, the nutritional status has been largely described as an important factor influencing the insulin/insulin-like growth factor signaling. It is now well established that the gut microbiota modulates the nutrient availability of its host. Hence, studies of the interaction between nutritional status, gut microbiota and bone growth have recently emerged. Here, we review recent findings using experimental models about the impact of gut bacteria on the somatotropic axis and its consequence on the bone growth. We also discuss the perspectives of these studies in opening an entire field for clinical interventions.

Obese Mice Losing Weight Due to trans-10,cis-12 Conjugated Linoleic Acid Supplementation or Food Restriction Harbor Distinct Gut Microbiota

Background

trans-10,cis-12 Conjugated linoleic acid (t10,c12-CLA) is a dietary supplement that promotes weight loss by increasing fat oxidation and energy expenditure. We previously reported that in the absence of t10,c12-CLA, mice forced to lose equivalent body weight by food restriction (FR) do not exhibit increases in fat oxidation or energy expenditure but have improved glucose metabolism, consistent with FR as a metabolically healthy weight-loss method.

Objective

Because diet is a primary determinant of gut bacterial populations, we hypothesized that the disparate metabolic effects accompanying weight loss from t10,c12-CLA or FR could be related to altered intestinal microbiota.

Methods

Ten-week-old male LDL receptor-deficient (Ldlr-/-) mice were fed a high-fat, high-sucrose diet (HFHS; 36% lard fat, 36.2% sucrose + 0.15% cholesterol) for 12 wk (baseline), then switched to the HFHS diet alone (obese control), HFHS + 1% c9,t11-CLA (obese fatty acid control), HFHS + 1% t10,c12-CLA (weight-loss-inducing fatty acid), or HFHS + FR (weight-loss control group with 75-85% ad libitum HFHS food intake) for a further 8 wk. Fecal microbial content, short-chain fatty acids (butyrate, acetate), tissue CLA concentrations, and intestinal nutrient transporter expression were quantified.

Results

Mice fed t10,c12-CLA or assigned to FR lost 14.5% of baseline body weight. t10,c12-CLA-fed mice had elevated concentrations of fecal butyrate (2-fold) and plasma acetate (1.5-fold) compared with HFHS-fed controls. Fecal α diversity decreased by 7.6-14% in all groups. Butyrivibrio and Roseburia, butyrate-producing microbes, were enriched over time by t10,c12-CLA. By comparing with each control group, we also identified bacterial genera significantly enriched in the t10,c12-CLA recipients, including Lactobacillus, Actinobacteria, and the newly identified Ileibacterium valens of the Allobaculum genus, whereas other taxa were enriched by FR, including Clostridiales and Bacteroides.

Conclusion

Modalities resulting in equivalent weight loss but with divergent metabolic effects are associated with compositional differences in the mouse intestinal microbiota.

Microbiota in obesity: interactions with enteroendocrine, immune and central nervous systems

Western diets, with high consumption of simple sugars and saturated fats, contribute to the rise in the prevalence of obesity. It now seems clear that high-fat diets cause obesity, at least in part, by modifying the composition and function of the microorganisms that colonize in the gastrointestinal tract, the microbiota. The exact pathways by which intestinal microbiota contribute to obesity remain largely unknown. High-fat diet-induced alterations in intestinal microbiota have been suggested to increase energy extraction, intestinal permeability and systemic inflammation while decreasing the capability to generate obesity-suppressing short-chain fatty acids. Moreover, by increasing systemic inflammation, microglial activation and affecting vagal nerve activity, 'obese microbiota' indirectly influence hypothalamic gene expression and promote overeating. Because the potential of intestinal microbiota to induce obesity has been recognized, multiple ways to modify its composition and function are being investigated to provide novel preventive and therapeutic strategies against diet-induced obesity.

Effects of probiotics on body weight, body mass index, fat mass and fat percentage in subjects with overweight or obesity: a systematic review and meta-analysis of randomized controlled trials

A systematic review and meta-analysis of randomized controlled trials was conducted to examine the effects of probiotic supplementation on body weight, body mass index (BMI), fat mass and fat percentage in subjects with overweight (BMI 25-29.9 kg m^-2 ) or obesity (BMI ≥30 kg m^-2 ). MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were searched for studies published between 1946 and September 2016. A meta-analysis, using a random effects model, was performed to calculate the weighted mean difference between the intervention and control groups. Of 800 studies identified through the literature search, 15 were finally included. The studies comprised a total of 957 subjects (63% women), with the mean BMI being 27.6 kg m^-2 and the duration of the interventions ranging from 3 to 12 weeks. Administration of probiotics resulted in a significantly larger reduction in body weight (weighted mean difference [95% confidence interval]; -0.60 [-1.19, -0.01] kg, I²  = 49%), BMI (-0.27 [-0.45, -0.08] kg m^-2 , I²  = 57%) and fat percentage (-0.60 [-1.20, -0.01] %, I²  = 19%), compared with placebo; however, the effect sizes were small. The effect of probiotics on fat mass was non-significant (-0.42 [-1.08, 0.23] kg, I²  = 84%).

Intestinal Lactobacillus in health and disease, a driver or just along for the ride?

Metagenomics and related methods have led to significant advances in our understanding of the human microbiome. Members of the genus Lactobacillus, although best understood for essential roles in food fermentations and applications as probiotics, have also come to the fore in a number of untargeted gut microbiome studies in humans and animals. Even though Lactobacillus is only a minor member of the human colonic microbiota, the proportions of those bacteria are frequently either positively or negatively correlated with human disease and chronic conditions. Recent findings on Lactobacillus species in human and animal microbiome research, together with the increased knowledge on probiotic and other ingested lactobacilli, have resulted in new perspectives on the importance of this genus to human health.

The Changes of Colonic Bacterial Composition and Bacterial Metabolism Induced by an Early Food Introduction in a Neonatal Porcine Model

The impact of an early food introduction on the microbiota composition and microbial metabolism in colon was investigated using a new-born piglet model. At day 4 after birth, 10 litters of piglets were randomly allocated to a sow-rearing group (SR group) and a milk-replacer supplementing group (MRS group) (n = 5). A commercial milk replacer was given to the suckling piglets in the MRS group from the 4th day to the 28th day. Pyrosequencing of the V3-V4 region of the 16S rRNA genes showed that the milk replacer supplementation significantly decreased the relative abundance of Lactobacillus, Clostridium XI, Blautia, Clostridium sensustricto and Escherichia (p = 0.08) in the colon of the piglets, but significantly increased the relative abundance of Paraprevotella on the 28th day. In addition, the abundance of Rumminococcus, Clostridium XlVa, Succiniclasticum, Clostridium IV tended to increase in the MRS group. The concentrations of acetate, propionate, butyrate, valerate and branch-chain fatty acids (BCFAs) in the colonic digesta increased with the milk replacer supplementary in the MRS group. In addition, the milk replacer supplementary increased the expression level of Toll-like receptor 4 (TLR4), but decreased the expression level of interleukin-6 (IL-6) in the colonic mucosa of the piglets. In conclusion, an early food introduction can influence the gut bacterial composition and metabolism, and may further affect the intestinal health by modifying the gene transcription related to the colonic function. These findings may provide some guidelines for the early nutrition supplementation for infants during the lactation period.

Gut Microbiota in Obesity and Metabolic Abnormalities: A Matter of Composition or Functionality?

The obesity pandemic and the metabolic complications derived from it represent a major public health challenge worldwide. Although obesity is a multifactorial disease, research from the past decade suggests that the gut microbiota interacts with host genetics and diet, as well as with other environmental factors, and thus contributes to the development of obesity and related complications. Despite abundant research on animal models, substantial evidence from humans has only started to accumulate over the past few years. Thus, the aim of the present review is to discuss structural and functional characteristics of the gut microbiome in human obesity, challenges associated with multi-omic technologies, and advances in identifying microbial metabolites with a direct link to obesity and metabolic complications. To date, studies suggests that obesity is related to low microbial diversity and taxon depletion sometimes resulting from an interaction with host dietary habits and genotype. These findings support the idea that the depletion or absence of certain taxa leaves an empty niche, likely leading to compromised functionality and thus promoting dysbiosis. Although the role of altered gut microbiota as cause or consequence of obesity remains controversial, research on microbial genomes and metabolites points towards an increased extraction of energy from the diet in obesity and suggests that metabolites, such as trimethylamine-N-oxide or branched-chain amino acids, participate in metabolic complications. Future research should be focused on structural and functional levels to unravel the mechanism linking gut microbiota and obesity.

Evidence based selection of probiotic strains to promote astronaut health or alleviate symptoms of illness on long duration spaceflight missions

Spaceflight impacts multiple aspects of human physiology, which will require non-invasive countermeasures as mission length and distance from Earth increases and the capability for external medical intervention decreases. Studies on Earth have shown that probiotics have the potential to improve some of the conditions that have manifested during spaceflight, such as gastrointestinal distress, dermatitis, and respiratory infections. The constraints and risks of spaceflight make it imperative that probiotics are carefully selected based on their strain-specific benefits, doses, delivery mechanisms, and relevance to likely crew conditions prior to evaluation in astronauts. This review focuses on probiotics that have been incorporated into healthy human gastrointestinal microbiomes and associated clinically with improvements in inflammatory state or alleviation of symptoms of crew-relevant illness. These studies provide an evidence base for probiotic selection with the greatest potential to support crew health and well-being in spaceflight.

Microbiome restoration diet improves digestion, cognition and physical and emotional wellbeing

Manipulating gut bacteria in the microbiome, through the use of probiotics and prebiotics, has been found to have an influence on both physical and emotional wellbeing. This study uses a dietary manipulation ‘The Gut Makeover’ designed to elicit positive changes to the gut bacteria within the microbiome. 21 healthy participants undertook ‘The Gut Makeover’ for a four week period. Weight and various aspects of health were assessed pre and post intervention using the Functional Medicine Medical Symptoms Questionnaire (MSQ). Paired sample t-tests revealed a significant reduction in self-reported weight at the end of the intervention. Adverse medical symptoms related to digestion, cognition and physical and emotional wellbeing, were also significantly reduced during the course of the dietary intervention. The intervention, designed to manipulate gut bacteria, had a significant impact on digestion, reducing IBS type symptoms in this non-clinical population. There was also a striking reduction in negative symptoms related to cognition, memory and emotional wellbeing, including symptoms of anxiety and depression. Dietary gut microbiome manipulations may have the power to exert positive physical and psychological health benefits, of a similar nature to those reported in studies using pre and probiotics. The small sample size and lack of control over confounding variables means that it will be important to replicate these findings in larger-scale controlled, prospective, clinical trials. This dietary microbiome intervention has the potential to improve physical and emotional wellbeing in the general population but also to be investigated as a treatment option for individuals with conditions as diverse as IBS, anxiety, depression and Alzheimer’s disease.

Can psychobiotics intake modulate psychological profile and body composition of women affected by normal weight obese syndrome and obesity? A double blind randomized clinical trial

Background

Evidence of probiotics effects on gut function, brain activity and emotional behaviour were provided. Probiotics can have dramatic effects on behaviour through the microbiome–gut–brain axis, through vagus nerve. We investigated whether chronic probiotic intake could modulate psychological state, eating behaviour and body composition of normal weight obese (NWO) and preobese–obese (PreOB/OB) compared to normal weight lean women (NWL).

Methods

60 women were enrolled. At baseline and after a 3-week probiotic oral suspension (POS) intake, all subjects underwent evaluation of body composition by anthropometry and dual X-ray absorptiometry, and psychological profile assessment by self-report questionnaires (i.e. EDI-2, SCL90R and BUT). Statistical analysis was carried out using paired t test or a non-parametric Wilcoxon test to evaluate differences between baseline and after POS intake, one-way ANOVA to compare all three groups and, where applicable, Chi square or t test were used to assess symptoms.

Results

Of the 48 women that concluded the study, 24% were NWO, 26% were NWL and 50% were PreOB/OB. Significant differences in body composition were highlighted among groups both at baseline and after a POS (p < 0.05). After POS intake, a significant reduction of BMI, resistance, FM (kg and %) (p < 0.05), and a significant increase of FFM (kg and  %) (p < 0.05) were observed in all subjects in NOW and PreOB/OB. After POS intake, reduction of bacterial overgrowth syndrome (p < 0.05) and lower psychopathological scores (p < 0.05) were observed in NWO and PreOB/OB women. At baseline and after POS intake, all subjects tested were negative to SCL90R_GSI scale, but after treatment subjects positive to BUT_GSI scale were significantly reduced (8.33%) (p < 0.05) compared to the baseline (33.30%). In NWO and PreOB/OB groups significant differences (p < 0.05) in response to the subscales of the EDI-2 were observed. Significant improvement of the orocecal transit time was observed (p < 0.05) after POS intake. Furthermore, significant differences were observed for meteorism (p < 0.05) and defecation frequency (p < 0.05).

Conclusions

A 3-week intake of selected psychobiotics modulated body composition, bacterial contamination, psychopathological scores of NWO and PreOB/OB women. Further research is needed on a larger population and for a longer period of treatment before definitive conclusions can be made.

Trial registration ClinicalTrials.gov Id: NCT01890070

Deleterious Metabolic Effects of High Fructose Intake: The Preventive Effect of Lactobacillus kefiri Administration

Modern lifestyle and diets have been associated with metabolic disorders and an imbalance in the normal gut microbiota. Probiotics are widely known for their health beneficial properties targeting the gut microbial ecosystem. The aim of our study was to evaluate the preventive effect of Lactobacillus kefiri (L. kefiri) administration in a fructose-rich diet (FRD) mice model. Mice were provided with tap water or fructose-added (20% w/v) drinking water supplemented or not with L. kefiri. Results showed that probiotic administration prevented weight gain and epidydimal adipose tissue (EAT) expansion, with partial reversion of the adipocyte hypertrophy developed by FRD. Moreover, the probiotic prevented the increase of plasma triglycerides and leptin, together with the liver triglyceride content. Leptin adipocyte secretion was also improved by L. kefiri, being able to respond to an insulin stimulus. Glucose intolerance was partially prevented by L. kefiri treatment (GTT) and local inflammation (TNFα; IL1β; IL6 and INFγ) was completely inhibited in EAT. L. kefiri supplementation generated an impact on gut microbiota composition, changing Bacteroidetes and Firmicutes profiles. Overall, our results indicate that the administration of probiotics prevents the deleterious effects of FRD intake and should therefore be promoted to improve metabolic disorders.

Microbes and Oxytocin: Benefits for Host Physiology and Behavior

It is now understood that gut bacteria exert effects beyond the local boundaries of the gastrointestinal tract to include distant tissues and overall health. Prototype probiotic bacterium Lactobacillus reuteri has been found to upregulate hormone oxytocin and systemic immune responses to achieve a wide array of health benefits involving wound healing, mental health, metabolism, and myoskeletal maintenance. Together these display that the gut microbiome and host animal interact via immune-endocrine-brain signaling networks. Such findings provide novel therapeutic strategies to stimulate powerful homeostatic pathways and genetic programs, stemming from the coevolution of mammals and their microbiome.