Bianca M. Arendt

Intestinal microbiota in patients with nonalcoholic fatty liver disease

Despite evidence that the intestinal microbiota (IM) is involved in the pathogenesis of obesity, the IM composition of patients with nonalcoholic fatty liver disease (NAFLD) has not been well characterized. This prospective, cross‐sectional study was aimed at identifying differences in IM between adults with biopsy‐proven NAFLD (simple steatosis [SS] or nonalcoholic steatohepatitis [NASH]) and living liver donors as healthy controls (HC). Fifty subjects were included: 11 SS, 22 NASH, and 17 HC. One stool sample was collected from each participant. Quantitative real‐time polymerase chain reaction was used to measure total bacterial counts, Bacteroides/Prevotella (herein referred to as Bacteroidetes), Clostridium leptum, C. coccoides, bifidobacteria, Escherichia coli and Archaea in stool. Clinical and laboratory data, food records, and activity logs were collected. Patients with NASH had a lower percentage of Bacteroidetes (Bacteroidetes to total bacteria counts) compared to both SS and HC (P = 0.006) and higher fecal C. coccoides compared to those with SS (P = 0.04). There were no differences in the remaining microorganisms. As body mass index (BMI) and dietary fat intake differed between the groups (P < 0.05), we performed linear regression adjusting for these variables. The difference in C. coccoides was no longer significant after adjusting for BMI and fat intake. However, there continued to be a significant association between the presence of NASH and lower percentage Bacteroidetes even after adjusting for these variables (P = 0.002; 95% confidence interval = −0.06 to −0.02).

Altered hepatic gene expression in nonalcoholic fatty liver disease is associated with lower hepatic n‐3 and n‐6 polyunsaturated fatty acids

In nonalcoholic fatty liver disease, hepatic gene expression and fatty acid (FA) composition have been reported independently, but a comprehensive gene expression profiling in relation to FA composition is lacking. The aim was to assess this relationship. In a cross‐sectional study, hepatic gene expression (Illumina Microarray) was first compared among 20 patients with simple steatosis (SS), 19 with nonalcoholic steatohepatitis (NASH), and 24 healthy controls. The FA composition in hepatic total lipids was compared between SS and NASH, and associations between gene expression and FAs were examined. Gene expression differed mainly between healthy controls and patients (SS and NASH), including genes related to unsaturated FA metabolism. Twenty‐two genes were differentially expressed between NASH and SS; most of them correlated with disease severity and related more to cancer progression than to lipid metabolism. Biologically active long‐chain polyunsaturated FAs (PUFAs; eicosapentaenoic acid + docosahexaenoic acid, arachidonic acid) in hepatic total lipids were lower in NASH than in SS. This may be related to overexpression of FADS1, FADS2, and PNPLA3. The degree and direction of correlations between PUFAs and gene expression were different among SS and NASH, which may suggest that low PUFA content in NASH modulates gene expression in a different way compared with SS or, alternatively, that gene expression influences PUFA content differently depending on disease severity (SS versus NASH). Conclusion: Well‐defined subjects with either healthy liver, SS, or NASH showed distinct hepatic gene expression profiles including genes involved in unsaturated FA metabolism. In patients with NASH, hepatic PUFAs were lower and associations with gene expression were different compared to SS. (Hepatology 2015;61:1565–1578)

The role of n − 6 and n − 3 polyunsaturated fatty acids in the manifestation of the metabolic syndrome in cardiovascular disease and non-alcoholic fatty liver disease

Cardiovascular disease (CVD) and non-alcoholic fatty liver disease (NAFLD) are manifestations of the metabolic syndrome. CVD remains the number one cause of mortality in the West, while NAFLD is the most common liver disease. Growing evidence suggests that polyunsaturated fatty acids (PUFA) influence risk factors including circulating lipids and inflammation on the development of CVD and NAFLD. N - 6 and n - 3 PUFA are comprised of distinct family members, which are increasingly recognized for their individual effects. Therefore, this review examines what is currently known about the specific effects of the major n - 3 and n - 6 PUFA on CVD and NAFLD. Overall, this review supports a beneficial effect of n - 3 PUFA and highlights distinctive effects between alpha-linolenic acid found in plant oils relative to marine derived eicosapentaenoic acid and docosahexaenoic acid. This review also highlights contrasting health effects between the n - 6 PUFA, linoleic and arachidonic acid.

Bile Acids and Dysbiosis in Non-Alcoholic Fatty Liver Disease.

Background & Aims Non-alcoholic fatty liver disease (NAFLD) is characterized by dysbiosis. The bidirectional effects between intestinal microbiota (IM) and bile acids (BA) suggest that dysbiosis may be accompanied by an altered bile acid (BA) homeostasis, which in turn can contribute to the metabolic dysregulation seen in NAFLD. This study sought to examine BA homeostasis in patients with NAFLD and to relate that with IM data. Methods This was a prospective, cross-sectional study of adults with biopsy-confirmed NAFLD (non-alcoholic fatty liver: NAFL or non-alcoholic steatohepatitis: NASH) and healthy controls (HC). Clinical and laboratory data, stool samples and 7-day food records were collected. Fecal BA profiles, serum markers of BA synthesis 7-alpha-hydroxy-4-cholesten-3-one (C4) and intestinal BA signalling, as well as IM composition were assessed. Results 53 subjects were included: 25 HC, 12 NAFL and 16 NASH. Levels of total fecal BA, cholic acid (CA), chenodeoxycholic acid (CDCA) and BA synthesis were higher in patients with NASH compared to HC (p<0.05 for all comparisons). The primary to secondary BA ratio was higher in NASH compared to HC (p = 0.004), but ratio of conjugated to unconjugated BAs was not different between the groups. Bacteroidetes and Clostridium leptum counts were decreased in in a subset of 16 patients with NASH compared to 25 HC, after adjusting for body mass index and weight-adjusted calorie intake (p = 0.028 and p = 0.030, respectively). C. leptum was positively correlated with fecal unconjugated lithocholic acid (LCA) (r = 0.526, p = 0.003) and inversely with unconjugated CA (r = -0.669, p<0.0001) and unconjugated CDCA (r = - 0.630, p<0.0001). FGF19 levels were not different between the groups (p = 0.114). Conclusions In adults with NAFLD, dysbiosis is associated with altered BA homeostasis, which renders them at increased risk of hepatic injury.

In Patients with HIV-Infection, Chromium Supplementation Improves Insulin Resistance and Other Metabolic Abnormalities: A Randomized, Double-Blind, Placebo Controlled Trial

Chromium is an essential micronutrient; chromium deficiency has been reported to cause insulin resistance, hyperglycemia and hyperlipidemia. The aim was to investigate the effect of chromium supplementation on insulin-resistance, other metabolic abnormalities, and body composition in people living with HIV. This was a randomized, double-blind, placebo-controlled trial. Fifty-two HIV-positive subjects with elevated glucose, lipids, or evidence of body fat redistribution, and who had insulin-resistance based on the calculation of homeostasis model of assessment (HOMA-IR > or = 2.5) were assessed. Subjects who were on insulin or hypoglycemic medications were excluded. Subjects were randomized to receive either 400 microg/day chromium-nicotinate or placebo for 16 weeks. Forty-six subjects, 23 in each group, completed the study. Fasting blood insulin, glucose, lipid profile and body composition were measured before and after intervention. Chromium was tolerated without side effects and resulted in a significant decrease in HOMA-IR (median (IQR) (pre:4.09 (3.02-8.79); post: 3.66 (2.40-5.46), p=0.004), insulin (pre: 102 (85-226); post: 99 (59-131) pmol/L, p=0.003), triglycerides, total body fat mass (mean+/-SEM) (pre: 17.3+/-1.7; post: 16.3+/-1.7 kg; p=0.002) and trunk fat mass (pre: 23.8+/-1.9; post: 22.7+/-2.0 %; p=0.008). Blood glucose, C-peptide, total, HDL and LDL cholesterol, and hemoglobin A1c remained unchanged. Biochemical parameters did not change in the placebo group except for LDL cholesterol which increased significantly. Body weight and medication profile remained stable throughout the study for both groups. In summary, chromium improved insulin resistance, metabolic abnormalities, and body composition in HIV+ patients. This suggests that chromium supplements alleviate some of the antiretroviral-associated metabolic abnormalities.

Nonalcoholic fatty liver disease is associated with lower hepatic and erythrocyte ratios of phosphatidylcholine to phosphatidylethanolamine

Nonalcoholic fatty liver disease (NAFLD) is associated with altered hepatic lipid composition. Animal studies suggest that the hepatic ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE) contributes to steatogenesis and inflammation. This ratio may be influenced by dysregulation of the PE N-methyltransferase (PEMT) pathway or by a low-choline diet. Alterations in the liver may also influence lipid composition in circulation such as in erythrocytes, which therefore may have utility as a biomarker of hepatic disease. Currently, no study has assessed both liver and erythrocyte PC/PE ratios in NAFLD. The aim of this study was to compare the PC/PE ratio in the liver and erythrocytes of patients with simple steatosis (SS) or nonalcoholic steatohepatitis (NASH) with that of healthy controls. PC and PE were measured by mass spectrometry in 28 patients with biopsy-proven NAFLD (14 SS, 14 NASH) and 9 healthy living liver donors as controls. The hepatic PC/PE ratio was lower in SS patients (median [range]) (1.23 [0.27-3.40]) and NASH patients (1.29 [0.77-3.22]) compared with controls (3.14 [2.20-3.73]); both p < 0.001) but it was not different between SS and NASH. PC was lower and PE higher in the liver of SS patients compared with controls, whereas in NASH patients only PE was higher. The PC/PE ratio in erythrocytes was also lower in SS and NASH patients compared with controls because of lower PC in both patient groups. PE in erythrocytes was not different among the groups. In conclusion, NAFLD patients have a lower PC/PE ratio in the liver and erythrocytes than do healthy controls, which may play a role in the pathogenesis. The underlying mechanisms require further investigation.

Effect of Atorvastatin, Vitamin E and C on Nonalcoholic Fatty Liver Disease: Is the Combination Required?

Nonalcoholic fatty liver disease is associated with the metabolic syndrome. The current standard of care, healthy diet and weight loss, has limited effect. The benefits of pharmacological treatments are unclear due to the difficulty of using liver histology as the main outcome in large randomized controlled trials (RCTs). In this issue, an RCT (1) with atorvastatin and antioxidants (vitamins E+C) vs. placebo shows improvement in liver steatosis based on computed tomography scans. The questions are (1) is this beneficial effect due to the combined treatment or the effect of an individual compound; (2) does this intervention improve nonalcoholic steatohepatitis.

Dietary Intake and Physical Activity in a Canadian Population Sample of Male Patients with HIV Infection and Metabolic Abnormalities

Objective was to assess dietary intake and physical activity in a Canadian population sample of male patients with HIV and metabolic abnormalities and to compare the data to Canadian recommendations. Sixty-five HIV-infected men with at least one feature associated with the metabolic syndrome (insulin resistance, dyslipidemia, central obesity, or lipodystrophy) were enrolled. Results from 7-day food records and activity logs were compared to the Dietary Reference Intakes and recommendations of Canadas Physical Activity Guide, respectively. Anthropometric data were also measured. Fifty-two percent of the subjects were overweight, another 15% were obese. However, energy intake (mean+/-SEM) (2153+/-99 kcal/d) was lower than the estimated requirement (2854+/-62 kcal/d; p<0.0001), and 84.5% of the patients reached the recommended minimum of 60 min of mild or 30 min of moderate daily exercise. Intake was adequate for protein, but high for fat and cholesterol in 40% of patients. No patient reached the recommendation for fiber. Intake from diet alone was suboptimal for most micronutrients. Prevalence was highest for low vitamin E (91% of patients) and magnesium (68%) intake, and high sodium intake (72%). In summary, a large proportion of HIV patients with metabolic abnormalities were overweight or obese. However, this was not associated with high energy intake, or reduced physical activity. High fat, low fiber and inadequate micronutrient intakes were prevalent.

Lung transplantation: does oxidative stress contribute to the development of bronchiolitis obliterans syndrome?

Lung transplantation is the ultimate treatment of end-stage lung disease. After transplantation, the 1-year survival rate is 80%. However, 5-year survival rates drop to 50% due to bronchiolitis obliterans syndrome (BOS). Ischemia/reperfusion injury, infections, and acute rejection are major risk factors contributing to the development of BOS. These risk factors are also associated with increased oxidative stress. Oxidative stress is a condition whereby prooxidants overwhelm the antioxidant defense system and may contribute to the pathogenesis of BOS by inducing more tissue injury and inflammation. This article reviews the current state of knowledge on oxidative stress in lung transplantation and BOS.

Hepatic Fatty Acid Composition Differs between Chronic Hepatitis C Patients with and without Steatosis

Hepatic fatty acid (FA) composition may influence steatosis development in patients with chronic hepatitis C (CHC). In a cross-sectional study, we compared the hepatic FA profile in hepatitis C patients with (n = 9) and without (n = 33) steatosis (> or =5% of hepatocytes involved). FA composition of hepatic and RBC total lipids was measured by gas chromatography. Lipid peroxidation and antioxidants in liver and plasma, blood biochemistry, and nutritional status were also assessed. Patients with steatosis had more fibrosis, higher necroinflammatory activity of their hepatitis C infection, were more often infected with genotype 3, and had lower serum cholesterol. Monounsaturated FA in the liver were higher and trans FA were lower in patients with steatosis. Lower stearic acid and higher oleic acid in hepatic total lipids suggested higher Delta9-desaturase activity. alpha-Linolenic acid in the liver was higher and the ratios of long-chain PUFA:essential FA precursors were lower for (n-3) and (n-6) PUFA. Plasma vitamin C was lower in steatosis, but RBC FA composition and other parameters did not differ. We conclude that hepatic FA composition is altered in patients with hepatitis C and steatosis, probably due to modulation of enzymatic elongation and desaturation. Oxidative stress or nutritional status does not seem to play a predominant role for development of steatosis in CHC.