Nonalcoholic steatohepatitis (NASH) is a serious liver disease associated with obesity. Characterized by metabolic syndrome, hepatic steatosis, and liver inflammation, NASH is believed to be under the influence of the gut microflora. Here, the composition of gut bacterial communities of NASH, obese, and healthy children was determined by 16S ribosomal RNA pyrosequencing. In addition, peripheral blood ethanol was analyzed to monitor endogenous ethanol production of patients and healthy controls. UniFrac-based principle coordinates analysis indicated that most of the microbiome samples clustered by disease status. Each group was associated with a unique pattern of enterotypes. Differences were abundant at phylum, family, and genus levels between healthy subjects and obese patients (with or without NASH), and relatively fewer differences were observed between obese and the NASH microbiomes. Among those taxa with greater than 1% representation in any of the disease groups, Proteobacteria, Enterobacteriaceae, and Escherichia were the only phylum, family and genus types exhibiting significant difference between obese and NASH microbiomes. Similar blood-ethanol concentrations were observed between healthy subjects and obese non-NASH patients, but NASH patients exhibited significantly elevated blood ethanol levels. Conclusions: The increased abundance of alcohol-producing bacteria in NASH microbiomes, elevated blood-ethanol concentration in NASH patients, and the well-established role of alcohol metabolism in oxidative stress and, consequently, liver inflammation suggest a role for alcohol-producing microbiota in the pathogenesis of NASH. We postulate that the distinct composition of the gut microbiome among NASH, obese, and healthy controls could offer a target for intervention or a marker for disease. (HEPATOLOGY 2013;57:601-609) N onalcoholic fatty liver disease (NAFLD), the hepatic manifestation of metabolic syndrome, is the most common cause of elevated liver enzymes in the United States.1 NAFLD with inflammation and fibrosis is known as nonalcoholic steatohepatitis (NASH) because it resembles alcoholic liver disease (ALD) without a history of alcohol ingestion. The incidence of NASH has been increasing over the past 20 years. 3 In the United States, the current prevalence of NAFLD and NASH could be as high as 46% and 12%, respectively. 4 Without an effective available treatment, the prognosis of NASH is not optimistic. NASH is responsible for approximately 10% of liver transplants in the United States and is projected to become the most common indication for liver transplantation in the near future.

The serum bile acid profile, the hepatic gene expression pattern and the gut microbiome composition consistently support an elevated bile acid production in NAFLD. The increased proportion of FXR antagonistic bile acid explains, at least in part, the suppression of hepatic FXR-mediated and FGFR4-mediated signalling. Our study suggests that future NAFLD intervention may target the components of FXR signalling, including the bile acid converting gut microbiome.

Previous studies using culture-based methods suggested an association between constipation and altered abundance of certain taxa of the colonic microbiome. We aim to examine the global changes in gut microbial composition of constipated patients. A cross-sectional pilot study using 16S rRNA gene pyrosequencing was performed to compare stool microbial composition of eight constipated patients and 14 nonconstipated controls. Only obese children were enrolled so that the microbiome features associated with constipation would not be obscured by those associated with obesity. The sequencing reads were processed by QIIME for quantitative analysis of the microbial composition at genus and above levels. Dietary intake for all the individuals was assessed by dietary recalls and a food frequency questionnaire. The ecological diversities of fecal microbiome of the constipated patients differed from those of the controls. Significantly decreased abundance in Prevotella and increased representation in several genera of Firmicutes were observed in constipated patients compared with controls. The conventional probiotic genera Lactobacillus and Bifidobacteria were not decreased in the microbiomes of the constipated patients. These alterations in the fecal microbiome of constipated patients suggested that a novel probiotic treatment including certain Prevotella strains may be more effective than conventional probiotic products incorporating Lactobacillus or Bifidobacterium species. While it is possible that the observed changes in the microbiome in constipated subjects are a consequence of a low-fiber diet, these changes also predict a different pattern of bacterial fermentation end-products, such as increased butyrate production, which may contribute to pathogenesis of constipation.

We study length-minimizing arcs in sub-Riemannian manifolds (M; E; G) whose metric G is de ned on a rank-two bracket-generating distribution E. It is well known that all length-minimizing arcs are extremals, and that these extremals are either \normal" or \abnormal." Normal extremals are locally optimal, in the sense that every suciently short piece of such an extremal is a minimizer. The question whether every length-minimizer is a normal extremal remained open for several years, and was recently settled by R. Montgomery, who exhibited a counterexample. But Montgomery's geometric optimality proof depends heavily on special properties of his example and still leaves open the question whether abnormal minimizers are an exceptional phenomenon or a common occurrence. We present an analytic technique for proving local optimality of a large class of abnormal extremals that we call \regular." Our technique is based on (a) a \normal form theorem," stating that, locally, a regular abnormal extremal can always be put in a special form by a suitable change of coordinates, and (b) an inequality showing that, once a trajectory is in this special form, then local optimality follows. Using this approach we prove that regular abnormal extremals are locally optimal. If E satis es a mild additional restriction |valid in particular for all regular 2-dimensional distributions and for generic 2-dimensional distributions| then regular abnormal extremals are \typical" (in a sense made precise in the text), so our result implies that the abnormal minimizers are ubiquitous rather than exceptional. We also discuss some related issues, and in particular show, by means of an example, that a smooth abnormal extremal need not be locally optimal, even if in addition it belongs to the class |recently studied by Bryant and Hsu| of C 1-rigid curves.

BackgroundNon-alcoholic steatohepatitis (NASH) is a serious form of non-alcoholic fatty liver disease (NAFLD), associated with obesity and insulin resistance. Previous studies suggested that intestinal bacteria produced more alcohol in obese mice than lean animals.Methodology/Principal FindingsTo investigate whether alcohol is involved in the pathogenesis of NASH, the expression of inflammation, fibrosis and alcohol metabolism related genes in the liver tissues of NASH patients and normal controls (NCs) were examined by microarray (NASH, n = 7; NC, n = 4) and quantitative real-time PCR (NASH, n = 6; NC, n = 6). Genes related to liver inflammation and fibrosis were found to be elevated in NASH livers compared to normal livers. The most striking finding is the increased gene transcription of alcohol dehydrogenase (ADH) genes, genes for catalase and cytochrome P450 2E1, and aldehyde dehydrogenase genes. Immunoblot analysis confirmed the increased expression of ADH1 and ADH4 in NASH livers (NASH, n = 9; NC, n = 4).Conclusions/SignificanceThe augmented activity of all the available genes of the pathways for alcohol catabolism suggest that 1) alcohol concentration was elevated in the circulation of NASH patients; 2) there was a high priority for the NASH livers to scavenge alcohol from the circulation. Our data is the first human evidence that suggests alcohol may contribute to the development of NAFLD.