ABSTRACT
BACKGROUND: Low-carbohydrate (e.g., Atkins) dietary pattern is one of the most effective diets for weight loss, but little is known about the characteristics of the gut microbiota accompanying low-carbohydrate diets-induced weight loss. This study aims to profile dynamics of gut bacteria and fungi accompanying modified Atkins diets-induced weight loss among overweight and obese adults. METHODS: Overweight and obese adults were screened to follow a modified Atkins diet plan (30% of energy from protein, 40% from carbohydrate and 30% from fat). We longitudinally profiled dynamics of gut bacteria and fungi based on 16S rRNA and ITS rRNA gene sequencing data, respectively. RESULTS: A total of 65 participants followed the modified Atkins diets for 20-231 days, with 61 and 27 participants achieving a weight loss of at least 5 and 10%, respectively. Most of the participants who achieved 10% weight loss also experienced improvements on metabolic health. The diversity of gut bacteria and fungi increased after a weight loss of 5% and kept stable thereafter. Bacteria genera including Lachnoclostridium and Ruminococcus 2 from Firmicutes phylum were depleted, while Parabacteroides and Bacteroides from Bacteroidetes phylum were enriched after weight loss. The inter-kingdom analysis found an intensive covariation between gut fungi and bacteria, involving more than half of the weight loss-associated bacteria. CONCLUSIONS: This study confirmed the modulation of bacterial and fungal composition during weight loss with the low-carbohydrate diets and showed previously unknown links between intestinal bacteria and fungi accompanying the weight loss.
ABSTRACT
BACKGROUND: Peroxisome proliferator activated receptor alpha (PPARα) ameliorates ethanol induced hepatic steatohepatitis. However, its role in alcoholic liver fibrosis has not been fully clarified. The aim of this study was to elucidate the effect and the molecular basis of PPARα in ethanol induced liver fibrosis in mice. METHODS: C57BL/6J mice were fed with 4% ethanol-containing Lieber-DeCarli liquid diet for eight weeks, and intraperitoneal injected with 5% carbon tetrachloride (CCl4) for the last four weeks to induce alcoholic liver fibrosis. PPARα agonist WY14643 was administered to mice during the last couple of weeks. The effects of PPARα induction on liver histology, activation of hepatic stellate cells (HSCs), as well as hepatic expression of inflammatory and fibrogenic factors were assessed. RESULTS: The ethanol plus CCl4 treated mice exhibited progressive liver injury including piecemeal necrosis of hepatocytes, severe inflammatory cells infiltration and bridging fibrosis. This was accompanied by down-regulated hepatic expression of PPARα and the protective cytokines adiponectin, heme oxygenase-1 and interleukin-10. Additionally, up-regulation of the proinflammatory cytokine tumor necrosis factor-alpha, as well as the profibrogenic genes osteopontin, transforming growth factor-beta 1, visfatin, phosphatidylinositol 3-kinase, matrix metalloproteinase-2 (MMP-2) and MMP-9 was observed. WY14643 treatment restored expression of cytokines altered by ethanol plus CCl4 treatment and concomitantly ameliorated the liver injury. CONCLUSIONS: The present study provides evidence for the protective role of PPARα induction in ameliorating ethanol mediated fibrosis through mediation of inflammatory and fibrogenic factors.
