A structured weight loss program increases gut microbiota phylogenetic diversity and reduces levels of Collinsella in obese type 2 diabetics: A pilot study

Abstract

The global obesity epidemic constitutes a major cause of morbidity and mortality challenging public health care systems worldwide. Thus, a better understanding of its pathophysiology and the development of novel therapeutic options are urgently needed. Recently, alterations of the intestinal microbiome in the obese have been discussed as a promoting factor in the pathophysiology of obesity and as a contributing factor to related diseases such as type 2 diabetes and metabolic syndrome. The present pilot study investigated the effect of a structured weight loss program on fecal microbiota in obese type 2 diabetics. Twelve study subjects received a low-calorie formula diet for six weeks, followed by a nine week food reintroduction and stabilization period. Fecal microbiota were determined by 16S rRNA gene sequencing of stool samples at baseline, after six weeks and at the end of the study after fifteen weeks. All study subjects lost weight continuously throughout the program. Changes in fecal microbiota were most pronounced after six weeks of low-calorie formula diet, but reverted partially until the end of the study. However, the gut microbiota phylogenetic diversity increased persistently. The abundance of Collinsella , which has previously been associated with atherosclerosis, decreased significantly during the weight loss program. This study underlines the impact of dietary changes on the intestinal microbiome and further demonstrates the beneficial effects of weight loss on gut microbiota. Trial registration: ClinicalTrials.gov NCT02970838 .

Effect of Short-Term Dietary Intervention and Probiotic Mix Supplementation on the Gut Microbiota of Elderly Obese Women

“…The Principal Coordinate Analysis (PCoA) of inter-individual variation, based on Bray-Curtis distances between the genus-level microbial profiles, nevertheless showed a significant separation between the study groups (p = 1 × 10 −5 , permutation test with pseudo-F ratios) ( Figure 1B). In line with the available literature on the gut microbiota in obesity and metabolic disorders in general [36][37][38][39][40][41], EO patients showed increased relative abundance of Coriobacteriaceae, especially Collinsella, and Streptococcus, as well as reduced proportions of a number of SCFA producers belonging to the Lachnospiraceae and Ruminococcaceae families, including the understudied Oscillospira (p ≤ 0.05, Wilcoxon test). In addition, significantly lower amounts of Parabacteroides, a bacterial genus to which anti-obesogenic effects have recently been attributed [42], were found in EO vs. EC subjects (p ≤ 0.004) ( Figure 2).…”

“…The Mediterranean diet is indeed considered the optimal strategy to prevent microbiota dysbiosis and protect intestinal permeability [55]. In line with the literature available on gut microbiota and metabolic disorders [36][37][38][39][40][41], the intestinal microbiota of EO subjects, as compared to non-obese elders (EC) living in the same territory (i.e., Italy), showed several dysbiotic features, including: (i) a tendency to reduced biodiversity (generally recognized as a hallmark of a healthy gut); (ii) decreased relative abundance of health-promoting, SCFA producers (mainly belonging to the Lachnospiraceae and Ruminococcaceae families, i.e., Lachnospira, Blautia, Coprococcus, Roseburia, Ruminococcus and Oscillospira) as well as Parabacteroides; and (iii) increased proportions of subdominant taxa, such as Collinsella and Streptococcus. While SCFAs are well known to have a key, multifactorial role in the host physiology, being fundamental for the maintenance of metabolic and immunological homeostasis [56], Collinsella and Streptococcus have been hypothesized to be involved in a variety of inflammation-based disorders [39,[57][58][59][60].…”

“…The underlying molecular mechanisms are still unknown but are likely to involve alteration of intestinal cholesterol absorption, reduction of glycogenesis in the liver and increase in triglyceride synthesis, as well as reduction of the expression of tight junction proteins, possibly leading to gut leakage and metabolic endotoxemia [37,61]. Although more direct evidence of Collinsella being pro-inflammatory, interfering with our metabolism and therefore being harmful to human health is needed, with the wave of enthusiasm in recent studies, Collinsella has been proposed as a target in future microbiome-based interventions for metabolic disorders [36]. A completely different role has instead been established for Oscillospira and Parabacteroides, with the first probably representing a heritable taxon capable of promoting leanness [40,47], and the second recently suggested as anti-obesogenic probiotics, capable of increasing adipose tissue thermogenesis, enhancing intestinal integrity and reducing levels of inflammation and insulin resistance [42].…”

Bariatric Surgery in Obesity: Effects on Gut Microbiota and Micronutrient Status

“…It is noteworthy that surgical treatment alone cannot account for improved MGR seen after BS, as other mechanisms (i.e., metabolic and inflammatory amelioration, weight loss, or diet) are thought to also contribute to this outcome. Indeed, short-term energy-restricted dietary intervention was shown to improve MGR in obese/overweight patients [67] and also to increase phylogenetic diversity in obese patients with type 2 diabetes [68]. Moreover, it is hypothesized that late weight regain and reappearance of obesity-related comorbidities documented in some bariatric patients might be linked with the lack of complete restoration of GM following BS [62].…”

Daily Intake of Paraprobiotic Lactobacillus amylovorus CP1563 Improves Pre-Obese Conditions and Affects the Gut Microbial Community in Healthy Pre-Obese Subjects: A Double-Blind, Randomized, Placebo-Controlled Study

“…The abundance of the genus Roseburia was negatively correlated with the plasma glucose levels in a human study [56], and the depletion of the genus Roseburia is a characteristic feature of the microbiome in type 2 diabetic patients [57]. In addition, a high abundance of the genus Collinsella is a characteristic feature of the microbiome in type 2 diabetic patients [58], and a structured weight loss program reduced the abundance of the genus Collinsella in obese type 2 diabetic patients [59]. Based on these insights, the alterations in the abundances of Roseburia and Collinsella observed in our study could have affected obesity in these patients.…”