Association between the ABO blood group and the human intestinal microbiota composition

ABSTRACT: BACKGROUND: The mucus layer covering the human intestinal epithelium forms a dynamic surface for host-microbial interactions. In addition to the environmental factors affecting the intestinal equilibrium, such as diet, it is well established that the microbiota composition is individually driven, but the host factors determining the composition have remained unresolved. RESULTS: In this study, we show that ABO blood group is involved in differences in relative proportion and overall profiles of intestinal microbiota. Specifically, the microbiota from the individuals harbouring the B antigen (secretor B and AB) differed from the non-B antigen groups and also showed higher diversity of the Eubacterium rectale-Clostridium coccoides (EREC) and Clostridium leptum (CLEPT) -groups in comparison with other blood groups. CONCLUSIONS: Our novel finding indicates that the ABO blood group is one of the genetically determined host factors modulating the composition of the human intestinal microbiota, thus enabling new applications in the field of personalized nutrition and medicine.     

In vitro effects of selected synbiotics on the human faecal microbiota composition

Synbiotics are recognized means of modulating gut microbiota composition and activities. However, whether synbiotics are superior to prebiotics and probiotics alone in moderating the gut microbiota towards a purportedly healthy composition has not been determined. Eight selected synbiotics (short-chain fructooligosaccharides or fructooligosaccharides, each combined with one of four probiotics, Lactobacillus fermentum ME-3, Lactobacillus plantarum WCFS1, Lactobacillus paracasei 8700:2 or Bifidobacterium longum 46) were added to 24-h pH-controlled anaerobic faecal batch cultures. The prebiotic and probiotic components were also tested alone to determine their respective role within the synbiotic for modulation of the faecal microbiota. Effects upon major groups of the microbiota were evaluated using FISH. Rifampicin variant probiotic strains were used to assess probiotic levels. Synbiotic and prebiotics increased bifidobacteria and the Eubacterium rectale-Clostridium coccoides group. Lower levels of Escherichia coli were retrieved with these combinations after 5 and 10 h of fermentation. Probiotics alone had little effect upon the groups, however. Multivariate analysis revealed that the effect of synbiotics differed from the prebiotics as higher levels of Lactobacillus-Enterococcus were observed when the probiotic was stimulated by the prebiotic component. Here, the synbiotic approach was more effective than prebiotic or probiotic alone to modulate the gut microbiota.     

Differences in fecal microbiota in different European study populations in relation to age, gender, and country: a cross-sectional study

A cross-sectional study on intestinal microbiota composition was performed on 230 healthy subjects at four European locations in France, Germany, Italy, and Sweden. The study participants were assigned to two age groups: 20 to 50 years (mean age, 35 years; n = 85) and >60 years (mean age, 75 years; n = 145). A set of 14 group- and species-specific 16S rRNA-targeted oligonucleotide probes was applied to the analysis of fecal samples by fluorescence in situ hybridization coupled with flow cytometry. Marked country-age interactions were observed for the German and Italian study groups. These interactions were inverse for the predominant bacterial groups Eubacterium rectale-Clostridium coccoides and Bacteroides-Prevotella. Differences between European populations were observed for the Bifidobacterium group only. Proportions of bifidobacteria were two- to threefold higher in the Italian study population than in any other study group, and this effect was independent of age. Higher proportions of enterobacteria were found in all elderly volunteers independent of the location. Gender effects were observed for the Bacteroides-Prevotella group, with higher levels in males than in females. In summary, age-related differences in the microbiota makeup were detected but differed between the study populations from the four countries, each showing a characteristic colonization pattern.     

The Microbiota of the Gut in Preschool Children With Normal and Excessive Body Weight

The aim of this study was to investigate the gut microbiota in preschool children with and without overweight and obesity. Twenty overweight or obese children and twenty children with BMI within the normal range (age: 4–5 years) were recruited from the south of Sweden. The gut microbiota was accessed by quantitative PCR (qPCR) and terminal restriction fragment length polymorphism and calprotectin was measured in feces. Liver enzymes were quantified in obese/overweight children. The concentration of the gram‐negative family Enterobacteriaceae was significantly higher in the obese/overweight children (P = 0.036), whereas levels of Desulfovibrio and Akkermansia muciniphila‐like bacteria were significantly lower in the obese/overweight children (P = 0.027 and P = 0.030, respectively). No significant differences were found in content of Lactobacillus, Bifidobacterium or the Bacteroides fragilis group. The diversity of the dominating bacterial community tended to be less diverse in the obese/overweight group, but the difference was not statistically significant. Concentration of Bifidobacterium was inversely correlated to alanine aminotransferase (ALT) in obese/overweight children. The fecal levels of calprotectin did not differ between the study groups. These findings indicate that the gut microbiota differed among preschool children with obesity/overweight compared with children with BMI within the normal range.     

Responses of gut microbiota to diet composition and weight loss in lean and obese mice

Maintenance of a reduced body weight is accompanied by a decrease in energy expenditure beyond that accounted for by reduced body mass and composition, as well as by an increased drive to eat. These effects appear to be due--in part--to reductions in circulating leptin concentrations due to loss of body fat. Gut microbiota have been implicated in the regulation of body weight. The effects of weight loss on qualitative aspects of gut microbiota have been studied in humans and mice, but these studies have been confounded by concurrent changes in diet composition, which influence microbial community composition. We studied the impact of 20% weight loss on the microbiota of diet-induced obese (DIO: 60% calories fat) mice on a high-fat diet (HFD). Weight-reduced DIO (DIO-WR) mice had the same body weight and composition as control (CON) ad-libitum (AL) fed mice being fed a control diet (10% calories fat), allowing a direct comparison of diet and weight-perturbation effects. Microbial community composition was assessed by pyrosequencing 16S rRNA genes derived from the ceca of sacrificed animals. There was a strong effect of diet composition on the diversity and composition of the microbiota. The relative abundance of specific members of the microbiota was correlated with circulating leptin concentrations and gene expression levels of inflammation markers in subcutaneous white adipose tissue in all mice. Together, these results suggest that both host adiposity and diet composition impact microbiota composition, possibly through leptin-mediated regulation of mucus production and/or inflammatory processes that alter the gut habitat.     

The Relationship between Endogenous Androgens and Body Fat Distribution in Early and Late Postmenopausal Women

Objectives

To investigate the relationship between endogenous androgens and body fat distribution in early and late postmenopausal women.

Materials and Methods

We enrolled postmenopausal women consisting of an early group (≤5 years since menopause, n = 105) and a late group (≥10 years since menopause, n = 107). Each group was subdivided into normal weight (BMI <24 kg/m²) group, overweight and obese (BMI ≥24 kg/m²) group. Fasting total testosterone (T), dehydroepiandrosterone-sulfate (DHEA-S) and sex hormone-binding globulin (SHBG) levels were measured. Body fat distribution was evaluated by dual-energy X-ray absorptiometry (DEXA).

Results

Late postmenopausal women had a higher proportion of body fat than early postmenopausal women. The body fat of the overweight and obese women had a greater tendency to accumulate in the abdomen compared with the normal weight women both in early and late postmenopausal groups. The overweight and obese women had a higher free testosterone (FT) than the normal weight women in early postmenopausal women (P<0.05). In late postmenopausal women, the overweight and obese women had higher DHEA-S levels than normal weight women (P<0.05). No direct relationship was observed between the T levels and body fat distribution both in early and late postmenopausal groups (P>0.05).The FT in early postmenopausal women and the DHEA-S levels in late postmenopausal women correlated positively with the trunk/leg fat ratio (T/L) and the proportion of android fat whereas correlated negatively with the proportion of gynoid fat in the partial correlation and multiple linear regression analyses (all P<0.05).

Conclusions

Serum T levels do not correlate directly with body fat distribution, the FT in early postmenopausal women and DHEA-S levels in late postmenopausal women correlate positively with abdominal fat accumulation.     

益生菌干预对肥胖孕鼠子代菌群及脂代谢的影响

目的分析高脂高糖饮食诱导肥胖母亲对子代菌群及脂代谢影响。方法C57BL/6J雌性小鼠30只随机分为正常对照组、肥胖组、益生菌干预组,每组10只。分别给予标准饲料、高脂高糖饲料以及高脂高糖饲料同时给予益生菌,连续喂养6周,制成肥胖母鼠模型。6周后雌、雄鼠合笼,受孕,孕期继续上述饮食。产后母乳喂养,3周后处死。留取雌性子鼠第21天粪便样本进行PCR-DGGE分析,同时酶反应比色法分析子鼠血脂情况。结果与正常对照组子代相比,肥胖母鼠子代菌群结构出现异常,益生菌干预组子代肠道菌群失调状况明显改善;肥胖母鼠子代血清总胆固醇、低密度脂蛋白含量升高,益生菌干预组子代血脂异常情况明显改善。结论高脂高糖饮食诱导肥胖母亲子代存在肠道菌群紊乱及脂代谢异常,益生菌干预母亲有利于改善子代菌群紊乱及脂代谢异常。     

Weight loss increases cardiovagal baroreflex function in obese young and older men

We tested the hypothesis that reductions in total body and abdominal visceral fat with energy restriction would be associated with increases in cardiovagal baroreflex sensitivity (BRS) in overweight/obese older men. To address this, overweight/obese (25 < or = body mass index < or = 35 kg/m(2)) young (OB-Y, n = 10, age = 32.9 +/- 2.3 yr) and older (OB-O, n = 6, age = 60 +/- 2.7 yr) men underwent 3 mo of energy restriction at a level designed to reduce body weight by 5-10%. Cardiovagal BRS (modified Oxford technique), body composition (dual-energy X-ray absorptiometry), and abdominal fat distribution (computed tomography) were measured in the overweight/obese men before weight loss and after 4 wk of weight stability at their reduced weight and compared with a group of nonobese young men (NO-Y, n = 13, age = 21.1 +/- 1.0 yr). Before weight loss, cardiovagal BRS was approximately 35% and approximately 60% lower (P < 0.05) in the OB-Y and OB-O compared with NO-Y. Body weight (-7.8 +/- 1.1 vs. -7.3 +/- 0.7 kg), total fat mass (-4.1 +/- 1.0 vs. -4.4 +/- 0.8 kg), and abdominal visceral fat (-27.6 +/- 6.9 vs. -43.5 +/- 10.1 cm(2)) were reduced (all P < 0.05) after weight loss, but the magnitude of reduction did not differ (all P > 0.05) between OB-Y and OB-O, respectively. Cardiovagal BRS increased (11.5 +/- 1.9 vs. 18.5 +/- 2.6 ms/mmHg and 6.7 +/- 1.2 vs. 12.8 +/- 4.2 ms/mmHg) after weight loss (both P < 0.05) in OB-Y and OB-O, respectively. After weight loss, cardiovagal BRS in the obese/overweight young and older men was approximately 105% and approximately 73% (P > 0.05) of NO-Y (17.5 +/- 2.2 ms/mmHg). Therefore, the results of this study indicate that weight loss increases the sensitivity of the cardiovagal baroreflex in overweight/obese young and older men.     

Diversity of the Clostridium coccoides group in human fecal microbiota as determined by 16S rRNA gene library

Fecal microbiota were analyzed in seven healthy individuals by 16S rRNA gene libraries (universal library) using universal primers, and the Clostridium coccoides group libraries using the universal primer 27F and the C. coccoides group-specific primer Erec482. The universal libraries were used in our previous studies. The 972 clones obtained from two different primer set libraries belonged to the C. coccoides group and were classified into 139 operational taxonomic units (OTU) (at least 98% sequence similarity). Of these, 41 OTU were detected commonly from universal libraries and C. coccoides group libraries. One hundred and ten OTU were detected from the C. coccoides group libraries. Fifteen new OTU were isolated from the C. coccoides group libraries in human gut. Most of the OTU did not correspond to known species, thus representing as-yet-uncultured bacteria. We also detected OTU that related to the butyrate-producing bacteria. The C. coccoides group consisted of an average of 35 OTU, although there were differences in the number and the type of species in each individual. When fecal microbiota were analyzed using universal libraries, the OTU belonging to the C. coccoides group detected in elderly individuals were fewer than those detected in adult individuals. When C. coccoides group libraries were used, the numbers of OTU in elderly and adult individuals were not different. Interindividual differences in the composition of OTU belonging to the C. coccoides group were also observed in fecal microbiota.     

Assessment of Abdominal Fat Compartments Using DXA in Premenopausal Women From Anorexia Nervosa to Morbid Obesity

Objective: To test a newly developed dual energy X‐ray absorptiometry (DXA) method for abdominal fat depot quantification in subjects with anorexia nervosa (AN), normal weight, and obesity using CT as a gold standard. Design and Methods: 135 premenopausal women (overweight/obese: n = 89, normal‐weight: n = 27, AN: n = 19); abdominal visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and total adipose tissue (TAT) areas determined on CT and DXA. Results: There were strong correlations between DXA and CT measurements of abdominal fat compartments in all groups with the strongest correlation coefficients in the normal‐weight and overweight/obese groups. Correlations of DXA and CT VAT measurements were strongest in the obese group and weakest in the AN group. DXA abdominal fat depots were higher in all groups compared to CT, with the largest % mean difference in the AN group and smallest in the obese group. Conclusion: A new DXA technique is able to assess abdominal fat compartments including VAT in premenopausal women across a large weight spectrum. However, DXA measurements of abdominal fat were higher than CT, and this percent bias was most pronounced in the AN subjects and decreased with increasing weight, suggesting that this technique may be more useful in obese individuals.     

Dietary Patterns Differently Associate with Inflammation and Gut Microbiota in Overweight and Obese Subjects

Background

Associations between dietary patterns, metabolic and inflammatory markers and gut microbiota are yet to be elucidated.

Objectives

We aimed to characterize dietary patterns in overweight and obese subjects and evaluate the different dietary patterns in relation to metabolic and inflammatory variables as well as gut microbiota.

Design

Dietary patterns, plasma and adipose tissue markers, and gut microbiota were evaluated in a group of 45 overweight and obese subjects (6 men and 39 women). A group of 14 lean subjects were also evaluated as a reference group.

Results

Three clusters of dietary patterns were identified in overweight/obese subjects. Cluster 1 had the least healthy eating behavior (highest consumption of potatoes, confectionary and sugary drinks, and the lowest consumption of fruits that was associated also with low consumption of yogurt, and water). This dietary pattern was associated with the highest LDL cholesterol, plasma soluble CD14 (p = 0.01) a marker of systemic inflammation but the lowest accumulation of CD163+ macrophages with anti-inflammatory profile in adipose tissue (p = 0.05). Cluster 3 had the healthiest eating behavior (lower consumption of confectionary and sugary drinks, and highest consumption of fruits but also yogurts and soups). Subjects in this Cluster had the lowest inflammatory markers (sCD14) and the highest anti-inflammatory adipose tissue CD163+ macrophages. Dietary intakes, insulin sensitivity and some inflammatory markers (plasma IL6) in Cluster 3 were close to those of lean subjects. Cluster 2 was in-between clusters 1 and 3 in terms of healthfulness. The 7 gut microbiota groups measured by qPCR were similar across the clusters. However, the healthiest dietary cluster had the highest microbial gene richness, as evaluated by quantitative metagenomics.

Conclusion

A healthier dietary pattern was associated with lower inflammatory markers as well as greater gut microbiota richness in overweight and obese subjects.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01314690","term_id":"NCT01314690"}}NCT01314690     

Real-time PCR quantification of the predominant bacterial divisions in the distal gut of Meishan and Landrace pigs

Firmicutes and Bacteroidetes are closely related to body fat in humans and mice, which are the two dominant bacterial divisions of gut microbiota in mammals. Here real-time PCR analysis indicated that Meishan pigs had a 34% reduction in percentage Bacteroidetes (P=0.008) and a significantly lower proportion of Bacteroides (P=0.013) than Landrace pigs. The percentage of Bacteroidetes or Bacteroides had a negative correlation with body fat (R(2) was 0.63 for Bacteroidetes and 0.57 for Bacteroides, P<0.05). There was a trend that the percentage of Firmicutes in Meishan pigs was higher in numerical value than in Landrace pigs, although this difference was not statistically significant (P=0.290) between the two breeds. These suggested that body fat correlated with the percentage of Bacteroidetes division of the gut microbiota in the common pig breeds, and the differences of gut microbial ecology in obese versus lean animals may be analogous.     

Changes in Gut Microbiota in Rats Fed a High Fat Diet Correlate with Obesity-Associated Metabolic Parameters

The gut microbiota is emerging as a new factor in the development of obesity. Many studies have described changes in microbiota composition in response to obesity and high fat diet (HFD) at the phylum level. In this study we used 16s RNA high throughput sequencing on faecal samples from rats chronically fed HFD or control chow (n = 10 per group, 16 weeks) to investigate changes in gut microbiota composition at the species level. 53.17% dissimilarity between groups was observed at the species level. Lactobacillus intestinalis dominated the microbiota in rats under the chow diet. However this species was considerably less abundant in rats fed HFD (P<0.0001), this being compensated by an increase in abundance of propionate/acetate producing species. To further understand the influence of these species on the development of the obese phenotype, we correlated their abundance with metabolic parameters associated with obesity. Of the taxa contributing the most to dissimilarity between groups, 10 presented significant correlations with at least one of the tested parameters, three of them correlated positively with all metabolic parameters: Phascolarctobacterium, Proteus mirabilis and Veillonellaceae, all propionate/acetate producers. Lactobacillus intestinalis was the only species whose abundance was negatively correlated with change in body weight and fat mass. This species decreased drastically in response to HFD, favouring propionate/acetate producing bacterial species whose abundance was strongly correlated with adiposity and deterioration of metabolic factors. Our observations suggest that these species may play a key role in the development of obesity in response to a HFD.     

Microbiota and SCFA in Lean and Overweight Healthy Subjects

Obesity has recently been linked to the composition of human microbiota and the production of short chain fatty acids (SCFAs). However, these findings rely on experimental studies carried out using rather small and defined groups of volunteers or model animals. Our aim was to evaluate differences within the human intestinal microbiota and fecal SCFA concentration of lean and obese subjects. A total of 98 subjects volunteered to take part in this study. The BMI in kg/m² of 30 volunteers was within the lean range, 35 were overweight and 33 were obese. The fecal microbiota was characterized by real‐time PCR analyses. With the primers used herein we were able to cover 82.3% (interquartile range of 68.3–91.4%) of the total microbiota detectable with a universal primer. In addition, the concentration of SCFA was evaluated. The total amount of SCFA was higher in the obese subject group (P = 0.024) than in the lean subject group. The proportion of individual SCFA changed in favor of propionate in overweight (P = 0.019) and obese subjects (P = 0.028). The most abundant bacterial groups in faeces of lean and obese subjects belonged to the phyla Firmicutes and Bacteroidetes. The ratio of Firmicutes to Bacteroidetes changed in favor of the Bacteroidetes in overweight (P = 0.001) and obese subjects (P = 0.005). Our results are in line with previous reports suggesting that SCFA metabolism might play a considerable role in obesity. However, our results contradict previous reports with regard to the contribution of various bacterial groups to the development of obesity and this issue remains controversial.     

Physical Activity Differentially Affects the Cecal Microbiota of Ovariectomized Female Rats Selectively Bred for High and Low Aerobic Capacity

The gut microbiota is considered a relevant factor in obesity and associated metabolic diseases, for which postmenopausal women are particularly at risk. Increasing physical activity has been recognized as an efficacious approach to prevent or treat obesity, yet the impact of physical activity on the microbiota remains under-investigated. We examined the impacts of voluntary exercise on host metabolism and gut microbiota in ovariectomized (OVX) high capacity (HCR) and low capacity running (LCR) rats. HCR and LCR rats (age = 27wk) were OVX and fed a high-fat diet (45% kcal fat) ad libitum and housed in cages equipped with (exercise, EX) or without (sedentary, SED) running wheels for 11wk (n = 7-8/group). We hypothesized that increased physical activity would hinder weight gain, increase metabolic health and shift the microbiota of LCR rats, resulting in populations more similar to that of HCR rats. Animals were compared for characteristic metabolic parameters including body composition, lipid profile and energy expenditure; whereas cecal digesta were collected for DNA extraction. 16S rRNA gene-based amplicon Illumina MiSeq sequencing was performed, followed by analysis using QIIME 1.8.0 to assess cecal microbiota. Voluntary exercise decreased body and fat mass, and normalized fasting NEFA concentrations of LCR rats, despite only running one-third the distance of HCR rats. Exercise, however, increased food intake, weight gain and fat mass of HCR rats. Exercise clustered the gut microbial community of LCR rats, which separated them from the other groups. Assessments of specific taxa revealed significant (p<0.05) line by exercise interactions including shifts in the abundances of Firmicutes, Proteobacteria, and Cyanobacteria. Relative abundance of Christensenellaceae family was higher (p = 0.026) in HCR than LCR rats, and positively correlated (p<0.05) with food intake, body weight and running distance. These findings demonstrate that exercise differentially impacts host metabolism and gut microbial communities of female HCR and LCR rats without ovarian function.     

Use of stable isotopes to measure the metabolic activity of the human intestinal microbiota

The human intestinal microbiota is a complex biological system comprising a vast repertoire of microbes with considerable metabolic activity relevant to both bacterial growth and host health. Greater strides have been made in the analysis of microbial diversity than in the measurement of functional activity, particularly in vivo. Stable isotope probing offers a new approach by coupling measurements of metabolic activity with microbial identification. Using a low-enrichment labeling strategy in vitro, this study has identified metabolically active bacterial groups via magnetic-bead capture methodology and stable isotope ratio analysis. Using five probes (EUB338, Bac303, Bif164, EREC482, and Clep866), changes in the activities of key intestinal microbial groups were successfully measured by exploiting tracers of de novo RNA synthesis. Perturbation of the nutrient source with oligofructose generated changes in the activity of bifidobacteria as expected, but also in the Bacteroides-Prevotella group, the Eubacterium rectale-Clostridium coccoides group, and the Clostridium leptum subgroup. Changes in activity were also observed in response to the medium type. This study suggests that changes in the functional activity of the gut microbiota can be assessed using tracers of de novo nucleic acid synthesis combined with measurement of low isotopic enrichment in 16S rRNA. Such tracers potentially limit substrate bias because they are universally available to bacteria. This low-enrichment labeling approach does not depend on the commercial availability of specific labeled substrates and can be easily translated to in vivo probing experiments of the functional activity of the microbiota in the human gut.     

Increased circadian prolactin release is blunted after body weight loss in obese premenopausal women

We recently showed that prolactin (PRL) release is considerably enhanced in obese women in proportion to the size of their visceral fat mass. PRL release is inhibited by dopamine 2 receptor (D2R) activation, and dietary restriction/weight loss are associated with increased dopaminergic signaling in animals. Therefore, we hypothesized that enhanced PRL release in obese humans would be reversed by weight loss. To evaluate this postulate, we measured 24-h plasma PRL concentrations at 10-min intervals in 11 obese premenopausal women (BMI 33.3 +/- 0.7 kg/m2) before and after weight loss (50% reduction of overweight/15% absolute weight loss, using a very low-calorie diet) in the follicular phase of their menstrual cycle. The 24-h PRL concentration profiles were analyzed by a peak detection program (Cluster) and a wave form-independent deconvolution technique (Pulse). Spontaneous 24-h PRL secretion was significantly reduced in obese women [mean daily release, before 128 +/- 24 vs. after weight loss 110 +/- 17 microg/liter distribution volume (Vdl)(-1) x 24 h, P = 0.05]. Body weight loss particularly blunted PRL secretory burst mass (Pulse area, before 230 +/- 28 vs. after weight loss 221 +/- 31 microg/Vdl(-1) x 24 h, P = 0.03), whereas burst frequency was unaffected (no. of pulses, before 11 +/- 1 vs. after weight loss 12 +/- 1 n/24 h, P = 0.69). Thus elevated PRL secretion rate in obese women is significantly reduced after loss of 50% of overweight. We speculate that amelioration of deficit D2R-mediated neurotransmission and/or diminutions of circulating leptin/estrogen levels might be involved in the physiology of this phenomenon.     

Combined hormonal contraceptives are associated with minor changes in composition and diversity in gut microbiota of healthy women

Recent human and animal studies have found associations between gut microbiota composition and serum levels of sex hormones, indicating that they could be an important factor in shaping the microbiota. However, little is known about the effect of regular hormonal fluctuations over the menstrual cycle or CHC-related changes of hormone levels on gut microbiota structure, diversity and dynamics. The aim of this study was to investigate the effect of CHCs on human gut microbiota composition. The effect of CHC pill intake on gut microbiota composition was studied in a group of seven healthy pre-menopausal women using the CHC pill, compared to the control group of nine age-matched healthy women that have not used hormonal contraceptives in the 6 months prior to the start of the study. By analysing the gut microbiota composition in both groups during one menstrual cycle, we found that CHC usage is associated with a minor decrease in gut microbiota diversity and differences in the abundance of several bacterial taxa. These results call for further investigation of the mechanisms underlying hormonal and hormonal contraceptive-related changes of the gut microbiota and the potential implications of these changes for women's health.     

不同身体质量指数人群肠道菌群结构及共存网络解析

[背景] 人体能量稳态失衡表现为体重过轻、超重和肥胖,肠道菌群与人体能量稳态的维持有关,但不同身体质量指数（Body Mass Index,BMI）人群的肠道菌群特征仍需进一步探究。[目的] 基于美国肠道计划公开数据库,解析4类BMI人群肠道菌群的特征,并探究4类BMI人群肠道菌群共存网络特征及差异,为基于肠道菌群来干预肥胖及体重过轻等不健康状态提供新的理论依据。[方法] 从美国肠道计划数据集中筛选具有BMI信息的肠道菌群样本,并根据世界卫生组织规定的BMI划分标准将筛选后的样本分为4类：体重过轻（BMI<18.5 kg/m²）,正常体重（18.5 kg/m²2）,超重（25 kg/m²2）,肥胖（BMI>30 kg/m²）;通过计算和比较肠道菌群的α多样性和β多样性探究4类BMI人群肠道菌群的整体结构特征及差异;通过多元线性回归模型对不同BMI分类与肠道菌群进行相关性分析,并且将地域、年龄、性别因素作为混杂因素加入到模型中进行校正;采用SparCC分别计算4类BMI人群肠道菌群中菌属相关性,并分别构建肠道菌群共存网络。[结果] 经过Wilcoxon秩和检验,发现体重过轻、超重、肥胖人群的肠道菌群α多样性都显著低于正常体重人群;β多样性分析结果表明4类BMI人群肠道菌群的整体结构存在显著差异;4类BMI人群肠道中厚壁菌门（Firmicutes）和拟杆菌门（Bacteroidetes）的相对含量无显著差异;通过MaAsLin分析,并且将地域、年龄、性别因素作为混杂因素加入到模型中进行校正,共得到49个与BMI类型显著相关的物种;4类BMI人群肠道菌群共存网络的拓扑结构具有一定差异,体重过轻和正常体重人群肠道菌群共存网络的复杂度较高,超重和肥胖人群肠道菌群共存网络的复杂度较低。[结论] 4类BMI人群肠道菌群的多样性、整体结构和共存网络间均存在差异。     

Alterations and structural resilience of the gut microbiota under dietary fat perturbations

Disequilibrium of the gut microbiota by dietary fat has been implicated in the incidence of overweight or obesity. However, it remains to be elucidated whether dietary fat perturbations in early life have long-lasting impacts on the gut microbiota and to what extent unbalanced diet-induced alterations in childhood are reversible. Accordingly, three groups of 1-day-old hens were used. They were fed with a low-fat diet (LFD), basal diet (BD) and high-fat diet (HFD), respectively, for 6 weeks and then switched to the same normal diets (NDs) for another 19 weeks. At week 6, hens in the LFD and HFD groups were found to have higher body weight, plasma glucose, total cholesterol, triglycerides and low-density lipoprotein cholesterol levels than their counterparts in the BD group, whereas upon switching to NDs, the metabolic deteriorations observed during the LFD consumption were alleviated. Principal component analysis revealed a shift of the gut microbiota structure in the LFD and HFD groups away from that of the BD group at week 6, while the gut microbiota structure of the LFD group was moved back to that of the BD group after reverting to NDs. Additionally, abnormal alterations of obesity-related phylotypes were observed in the LFD and HFD groups, whereas the abundance of these phylotypes in the LFD group was almost reverted to the BD levels over time. Collectively, dietary fat perturbations in early life have long-term impacts on hosts, and the structural resilience of the gut microbiota in hens fed with HFD was lower than that in their LFD counterparts.