Gut microbiota and fermentation-derived branched chain hydroxy acids mediate health benefits of yogurt consumption in obese mice.

Meta-analyses suggest that yogurt consumption reduces type 2 diabetes incidence in humans, but the molecular basis of these observations remains unknown. Here we show that dietary yogurt intake preserves whole-body glucose homeostasis and prevents hepatic insulin resistance and liver steatosis in a dietary mouse model of obesity-linked type 2 diabetes. Fecal microbiota transplantation studies reveal that these effects are partly linked to the gut microbiota. We further show that yogurt intake impacts the hepatic metabolome, notably maintaining the levels of branched chain hydroxy acids (BCHA) which correlate with improved metabolic parameters. These metabolites are generated upon milk fermentation and concentrated in yogurt. Remarkably, diet-induced obesity reduces plasma and tissue BCHA levels, and this is partly prevented by dietary yogurt intake. We further show that BCHA improve insulin action on glucose metabolism in liver and muscle cells, identifying BCHA as cell-autonomous metabolic regulators and potential mediators of yogurt's health effects.

Yoghurt consumption is associated with changes in the composition of the human gut microbiome and metabolome.

BACKGROUND: Yoghurt contains live bacteria that could contribute via modulation of the gut microbiota to its reported beneficial effects such as reduced body weight gain and lower incidence of type 2 diabetes. To date, the association between yoghurt consumption and the composition of the gut microbiota is underexplored. Here we used clinical variables, metabolomics, 16S rRNA and shotgun metagenomic sequencing data collected on over 1000 predominantly female UK twins to define the link between the gut microbiota and yoghurt-associated health benefits. RESULTS: According to food frequency questionnaires (FFQ), 73% of subjects consumed yoghurt. Consumers presented a healthier diet pattern (healthy eating index: beta = 2.17 ± 0.34; P = 2.72x10-10) and improved metabolic health characterised by reduced visceral fat (beta = -28.18 ± 11.71 g; P = 0.01). According to 16S rRNA gene analyses and whole shotgun metagenomic sequencing approach consistent taxonomic variations were observed with yoghurt consumption. More specifically, we identified higher abundance of species used as yoghurt starters Streptococcus thermophilus (beta = 0.41 ± 0.051; P = 6.14x10-12) and sometimes added Bifidobacterium animalis subsp. lactis (beta = 0.30 ± 0.052; P = 1.49x10-8) in the gut of yoghurt consumers. Replication in 1103 volunteers from the LifeLines-DEEP cohort confirmed the increase of S. thermophilus among yoghurt consumers. Using food records collected the day prior to faecal sampling we showed than an increase in these two yoghurt bacteria could be transient. Metabolomics analysis revealed that B. animalis subsp. lactis was associated with 13 faecal metabolites including a 3-hydroxyoctanoic acid, known to be involved in the regulation of gut inflammation. CONCLUSIONS: Yoghurt consumption is associated with reduced visceral fat mass and changes in gut microbiome including transient increase of yoghurt-contained species (i.e. S. thermophilus and B. lactis).

A posteriori dietary patterns better explain variations of the gut microbiome than individual markers in the American Gut Project.

BACKGROUND: Individual diet components and specific dietary regimens have been shown to impact the gut microbiome. OBJECTIVES: Here, we explored the contribution of long-term diet by searching for dietary patterns that would best associate with the gut microbiome in a population-based cohort. METHODS: Using a priori and a posteriori approaches, we constructed dietary patterns from an FFQ completed by 1800 adults in the American Gut Project. Dietary patterns were defined as groups of participants or combinations of food variables (factors) driven by criteria ranging from individual nutrients to overall diet. We associated these patterns with 16S ribosomal RNA-based gut microbiome data for a subset of 744 participants. RESULTS: Compared to individual features (e.g., fiber and protein), or to factors representing a reduced number of dietary features, 5 a posteriori dietary patterns based on food groups were best associated with gut microbiome beta diversity (P ≤ 0.0002). Two patterns followed Prudent-like diets-Plant-Based and Flexitarian-and exhibited the highest Healthy Eating Index 2010 (HEI-2010) scores. Two other patterns presented Western-like diets with a gradient in HEI-2010 scores. A fifth pattern consisted mostly of participants following an Exclusion diet (e.g., low carbohydrate). Notably, gut microbiome alpha diversity was significantly lower in the most Western pattern compared to the Flexitarian pattern (P ≤ 0.009), and the Exclusion diet pattern was associated with low relative abundance of Bifidobacterium (P ≤ 1.2 × 10-7), which was better explained by diet than health status. CONCLUSIONS: We demonstrated that global-diet a posteriori patterns were more associated with gut microbiome variations than individual dietary features among adults in the United States. These results confirm that evaluating diet as a whole is important when studying the gut microbiome. It will also facilitate the design of more personalized dietary strategies in general populations.

Impact of bacterial probiotics on obesity, diabetes and non-alcoholic fatty liver disease related variables: a systematic review and meta-analysis of randomised controlled trials.

OBJECTIVE: To systematically review the effect of oral intake of bacterial probiotics on 15 variables related to obesity, diabetes and non-alcoholic fatty liver disease. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Medline, EMBASE and COCHRANE from 1990 to June 2018. ELIGIBILITY CRITERIA: Randomised controlled trials (≥14 days) excluding hypercholesterolaemia, alcoholic liver disease, polycystic ovary syndrome and children <3 years. RESULTS: One hundred and five articles met inclusion criteria, representing 6826 subjects. In overweight but not obese subjects, probiotics induced improvements in: body weight (k=25 trials, d=-0.94 kg mean difference, 95% CI -1.17 to -0.70, I²=0.0%), body mass index (k=32, d=-0.55 kg/m², 95% CI -0.86 to -0.23, I²=91.9%), waist circumference (k=13, d=-1.31 cm, 95% CI -1.79 to -0.83, I²=14.5%), body fat mass (k=11, d=-0.96 kg, 95% CI -1.21 to -0.71, I²=0.0%) and visceral adipose tissue mass (k=5, d=-6.30 cm², 95% CI -9.05 to -3.56, I²=0.0%). In type 2 diabetics, probiotics reduced fasting glucose (k=19, d=-0.66 mmol/L, 95% CI -1.00 to -0.31, I²=27.7%), glycated haemoglobin (k=13, d=-0.28 pp, 95% CI -0.46 to -0.11, I²=54.1%), insulin (k=13, d=-1.66 mU/L, 95% CI -2.70 to -0.61, I²=37.8%) and homeostatic model of insulin resistance (k=10, d=-1.05 pp, 95% CI -1.48 to -0.61, I²=18.2%). In subjects with fatty liver diseases, probiotics reduced alanine (k=12, d=-10.2 U/L, 95% CI -14.3 to -6.0, I²=93.50%) and aspartate aminotransferases (k=10, d=-9.9 U/L, 95% CI -14.1 to -5.8, I²=96.1%). These improvements were mostly observed with bifidobacteria (Bifidobacterium breve, B. longum), Streptococcus salivarius subsp. thermophilus and lactobacilli (Lactobacillus acidophilus, L. casei, L. delbrueckii) containing mixtures and influenced by trials conducted in one country. CONCLUSIONS: The intake of probiotics resulted in minor but consistent improvements in several metabolic risk factors in subjects with metabolic diseases. TRIAL REGISTRATION NUMBER: CRD42016033273.

Opportunistic Infections in HIV-Infected Patients Differ Strongly in Frequencies and Spectra between Patients with Low CD4+ Cell Counts Examined Postmortem and Compensated Patients Examined Antemortem Irrespective of the HAART Era.

OBJECTIVE: AIDS-related mortality has changed dramatically with the onset of highly active antiretroviral therapy (HAART), which has even allowed compensated HIV-infected patients to withdraw from secondary therapy directed against opportunistic pathogens. However, in recently autopsied HIV-infected patients, we observed that associations with a broad spectrum of pathogens remain, although detailed analyses are lacking. Therefore, we focused on the possible frequency and spectrum shifts in pathogens associated with autopsied HIV-infected patients. DESIGN: We hypothesized that the pathogens frequency and spectrum changes found in HIV-infected patients examined postmortem did not recapitulate the changes found previously in HIV-infected patients examined antemortem in both the pre- and post-HAART eras. Because this is the first comprehensive study originating from Central and Eastern Europe, we also compared our data with those obtained in the West and Southwest Europe, USA and Latin America. METHODS: We performed autopsies on 124 HIV-infected patients who died from AIDS or other co-morbidities in the Czech Republic between 1985 and 2014. The pathological findings were retrieved from the full postmortem examinations and autopsy records. RESULTS: We collected a total of 502 host-pathogen records covering 82 pathogen species, a spectrum that did not change according to patients' therapy or since the onset of the epidemics, which can probably be explained by the fact that even recently deceased patients were usually decompensated (in 95% of the cases, the last available CD4+ cell count was falling below 200 cells*µl-1) regardless of the treatment they received. The newly identified pathogen taxa in HIV-infected patients included Acinetobacter calcoaceticus, Aerococcus viridans and Escherichia hermannii. We observed a very limited overlap in both the spectra and frequencies of the pathogen species found postmortem in HIV-infected patients in Europe, the USA and Latin America. CONCLUSIONS: The shifts documented previously in compensated HIV-infected patients examined antemortem in the post-HAART era are not recapitulated in mostly decompensated HIV-infected patients examined postmortem.

Form of phytosterols and food matrix in which they are incorporated modulate their incorporation into mixed micelles and impact cholesterol micellarization.

SCOPE: The ability of different plant sterols/stanols (PS) mixtures, which differed in the degree of B-ring saturation and aliphatic side chain structure and saturation, to reduce cholesterol (CH) micellarization was explored. METHODS AND RESULTS: Experiments were performed using an in vitro digestion model, synthetic mixed micelles, and pure porcine pancreatic lipases. Sterols were measured by GC-FID. The ability of PS to reduce CH micellarization was dependent on the form of PS and on the type of delivery matrix (low-fat yogurt or olive oil). Long-chain PS esters delivered in the yogurt matrix, and medium chain PS esters delivered in olive oil provided the greatest reduction in CH micellarization. In yogurt, the ability to impair CH micellarization was inversely related (rho = -0.41, p < 0.0005) to PS melting point. In olive oil, the more hydrophobic PS mixtures, i.e. those rich in long-chain PS esters, had the lower ability to impair CH micellarization. CONCLUSIONS: Different forms of PS have a different ability to impair CH micellarization. This ability depends on the transfer efficiency of PS from the food matrix to the micelle, which in turn depends on the melting point and the hydrophobicity of PS and on the delivery food matrix.

Systems genetics of metabolism: the use of the BXD murine reference panel for multiscalar integration of traits.

Metabolic homeostasis is achieved by complex molecular and cellular networks that differ significantly among individuals and are difficult to model with genetically engineered lines of mice optimized to study single gene function. Here, we systematically acquired metabolic phenotypes by using the EUMODIC EMPReSS protocols across a large panel of isogenic but diverse strains of mice (BXD type) to study the genetic control of metabolism. We generated and analyzed 140 classical phenotypes and deposited these in an open-access web service for systems genetics (www.genenetwork.org). Heritability, influence of sex, and genetic modifiers of traits were examined singly and jointly by using quantitative-trait locus (QTL) and expression QTL-mapping methods. Traits and networks were linked to loci encompassing both known variants and novel candidate genes, including alkaline phosphatase (ALPL), here linked to hypophosphatasia. The assembled and curated phenotypes provide key resources and exemplars that can be used to dissect complex metabolic traits and disorders.

Ppargamma2 is a key driver of longevity in the mouse.

Aging involves a progressive physiological remodeling that is controlled by both genetic and environmental factors. Many of these factors impact also on white adipose tissue (WAT), which has been shown to be a determinant of lifespan. Interrogating a transcriptional network for predicted causal regulatory interactions in a collection of mouse WAT from F2 crosses with a seed set of 60 known longevity genes, we identified a novel transcriptional subnetwork of 742 genes which represent thus-far-unknown longevity genes. Within this subnetwork, one gene was Pparg (Nr1c3), an adipose-enriched nuclear receptor previously not associated with longevity. In silico, both the PPAR signaling pathway and the transcriptional signature of Ppargamma agonist rosiglitazone overlapped with the longevity subnetwork, while in vivo, lowered expression of Pparg reduced lifespan in both the lipodystrophic Pparg1/2-hypomorphic and the Pparg2-deficient mice. These results establish Ppargamma2 as one of the determinants of longevity and suggest that lifespan may be rather determined by a purposeful genetic program than a random process.

Identification of the UBP1 locus as a critical blood pressure determinant using a combination of mouse and human genetics.

Hypertension is a major health problem of largely unknown genetic origins. To identify new genes responsible for hypertension, genetic analysis of recombinant inbred strains of mice followed by human association studies might prove powerful and was exploited in our current study. Using a set of 27 recombinant BXD strains of mice we identified a quantitative trait locus (QTL) for blood pressure (BP) on distal chromosome 9. The association analysis of markers encompassing the syntenic region on human chromosome 3 gave in an additive genetic model the strongest association for rs17030583 C/T and rs2291897 G/A, located within the UBP1 locus, with systolic and diastolic BP (rs17030583: 1.3+/-0.4 mmHg p<0.001, 0.8+/-0.3 mmHg p = 0.006, respectively and rs2291897: 1.5+/-0.4 mmHg p<0.001, 0.8+/-0.3 mmHg p = 0.003, respectively) in three separate studies. Our study, which underscores the marked complementarities of mouse and human genetic approaches, identifies the UBP1 locus as a critical blood pressure determinant. UBP1 plays a role in cholesterol and steroid metabolism via the transcriptional activation of CYP11A, the rate-limiting enzyme in pregnenolone and aldosterone biosynthesis. We suggest that UBP1 and its functional partners are components of a network controlling blood pressure.

The Pro12Ala PPARgamma2 variant determines metabolism at the gene-environment interface.

The metabolic impact of the common peroxisome proliferator-activated receptor gamma isoform 2 (PPARgamma2) variant Pro12Ala in human populations has been widely debated. We demonstrate, using a Pro12Ala knockin model, that on chow diet, Ala/Ala mice are leaner, have improved insulin sensitivity and plasma lipid profiles, and have longer lifespans. Gene-environment interactions played a key role as high-fat feeding eliminated the beneficial effects of the Pro12Ala variant on adiposity, plasma lipids, and insulin sensitivity. The underlying molecular mechanisms involve changes in cofactor interaction and adiponectin signaling. Altogether, our results establish the Pro12Ala variant of Ppargamma2 as an important modulator in metabolic control that strongly depends on the metabolic context.

Visceral obesity is associated with high levels of serum squalene.

OBJECTIVE: To investigate the impact of visceral obesity on cholesterol metabolism in normoglycemic offspring of patients with type 2 diabetes. RESEARCH METHODS AND PROCEDURES: The proportion of intra-abdominal fat (IAF) was measured by abdominal computer tomography, and serum cholesterol synthesis and absorption markers were determined by gas-liquid chromatography in 109 normoglycemic offspring of patients with type 2 diabetes. Insulin action was measured with the hyperinsulinemic euglycemic clamp. The gene encoding squalene synthase (farnesyl-diphosphate farnesyltransferase 1) was screened with the single-strand conformation polymorphism analysis and direct sequencing. RESULTS: Cholesterol synthesis markers correlated positively with IAF (r = 0.213 to 0.309, p < or = 0.027) and negatively with the rates of insulin-stimulated whole-body glucose uptake (r = -0.372 to -0.248, p < or = 0.010). However, serum squalene, the first measured precursor of cholesterol synthesis, showed a positive correlation with IAF (r = 0.309, p = 0.001) without any association with subcutaneous fat or insulin sensitivity. Variation in the farnesyl-diphosphate farnesyltransferase 1 gene did not explain elevated serum squalene levels in viscerally obese subjects. From the cholesterol absorption markers, cholestanol was associated negatively with IAF and positively with whole-body glucose uptake (p < 0.05). DISCUSSION: High serum squalene levels are associated with visceral obesity but not with subcutaneous obesity. Whether this finding is causally connected to visceral obesity remains to be established.

Adipose tissue expression of the lipid droplet-associating proteins S3-12 and perilipin is controlled by peroxisome proliferator-activated receptor-gamma.

In a systematic search for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) target genes, we identified S3-12 and perilipin as novel direct PPAR-gamma target genes. Together with adipophilin and tail-interacting protein of 47 kDa, these genes are lipid droplet-associating proteins with distinct expression pattern but overlapping expression in adipose tissue. The expression of S3-12 and perilipin is tightly correlated to the expression and activation of PPAR-gamma in adipocytes, and promoter characterization revealed that the S3-12 and the perilipin promoters contain three and one evolutionarily conserved PPAR response elements, respectively. We furthermore demonstrate that the expression of S3-12 and perilipin is reduced in obese compared with lean Zucker rats, whereas the expression of adipophilin is increased. Others have shown that perilipin is an essential factor in the hormonal regulation of lipolysis of stored triglycerides within adipose tissue. The direct regulation of perilipin and S3-12 by PPAR-gamma therefore is likely to be an important mediator of the in vivo effects of prolonged treatment with PPAR-gamma activators: insulin sensitization, fatty acid trapping in adipose tissue, reduced basal adipose lipolysis, and weight gain.

Compensation by the muscle limits the metabolic consequences of lipodystrophy in PPAR gamma hypomorphic mice.

Peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor, which controls adipocyte differentiation. We targeted with homologous recombination the PPAR gamma 2-specific exon B, resulting in a white adipose tissue knockdown of PPAR gamma. Although homozygous (PPAR gamma hyp/hyp) mice are born with similar weight as the WT mice, the PPAR gamma hyp/hyp animals become growth retarded and develop severe lipodystrophy and hyperlipidemia. Almost half of these PPAR gamma hyp/hyp mice die before adulthood, whereas the surviving PPAR gamma hyp/hyp animals overcome the growth retardation, yet remain lipodystrophic. In contrast to most lipodystrophic models, the adult PPAR gamma hyp/hyp mice only have mild glucose intolerance and do not have a fatty liver. These metabolic consequences of the lipodystrophy are relatively benign because of the induction of a compensatory gene expression program in the muscle that enables efficient oxidation of excess lipids. The PPAR gamma hyp/hyp mice unequivocally demonstrate that PPAR gamma is the master regulator of adipogenesis in vivo and establish that lipid and glucose homeostasis can be relatively well maintained in the absence of white adipose tissue.

The p38 subunit of the aminoacyl-tRNA synthetase complex is a Parkin substrate: linking protein biosynthesis and neurodegeneration.

Parkinson's disease (PD) is a severe neurological disorder, characterized by the progressive degeneration of the dopaminergic nigrostriatal pathway and the presence of Lewy bodies (LBs). The discovery of genes responsible for familial forms of the disease has provided insights into its pathogenesis. Mutations in the parkin gene, which encodes an E3 ubiquitin-protein ligase involved in the ubiquitylation and proteasomal degradation of specific protein substrates, have been found in nearly 50% of patients with autosomal-recessive early-onset parkinsonism. The abnormal accumulation of substrates due to loss of Parkin function may be the cause of neurodegeneration in parkin-related parkinsonism. Here, we demonstrate that Parkin interacts with, ubiquitylates and promotes the degradation of p38, a key structural component of the mammalian aminoacyl-tRNA synthetase complex. We found that the ubiquitylation of p38 is abrogated by truncated variants of Parkin lacking essential functional domains, but not by the pathogenic Lys161Asn point mutant. Expression of p38 in COS7 cells resulted in the formation of aggresome-like inclusions in which Parkin was systematically sequestered. In the human dopaminergic neuroblastoma-derived SH-SY5Y cell line, Parkin promoted the formation of ubiquitylated p38-positive inclusions. Moreover, the overexpression of p38 in SH-SY5Y cells caused significant cell death against which Parkin provided protection. Analysis of p38 expression in the human adult midbrain revealed strong immunoreactivity in normal dopaminergic neurons and the labeling of LBs in idiopathic PD. This suggests that p38 plays a role in the pathogenesis of PD, opening the way for a detailed examination of its potential non-canonical role in neurodegeneration.

PPARgamma, an X-ceptor for Xs.

Evidence from both human genetic studies and characterization of peroxisome proliferator-activated receptor gamma (PPARgamma) knockout mice suggested that the prime function of PPARgamma is fat formation and that its role in insulin sensitization might be secondary to this function. The thrifty function of PPARgamma was most likely evolutionary beneficial, but might in "times of plenty" contribute to the pathogenesis of disorders, such as obesity, insulin resistance, type 2 diabetes, and hyperlipidemia, often commonly referred to as "syndrome X". This role of PPARgamma in these diseases also questions the eventual therapeutic benefits of pure PPARgamma activation, which is associated with an increase in adipose tissue mass. We characterized a new chemical class of PPARgamma agonists, that is, FMOC-l-leucine (FLL). FLL induces a different conformation of PPARgamma relative to classical PPARgamma ligands. Mass spectrometry indicates that two molecules of FLL bind to a single PPARgamma molecule, making its mode of receptor interaction distinctive. FLL recruits a different set of coactivators and activates PPARgamma with a lower potency, but a similar maximal efficacy, relative to known PPARgamma ligands. In contrast, FLL is a more effective insulin sensitizer than current PPARgamma agonists, an effect potentially linked to its weak adipogenic activity. These data make a strong point for potential therapeutic benefits of PPARgamma modulation rather than activation.